Was the Soviet Union in 1945 seeking to capture German soldiers and civilians, or drive them west?

This is subjective question which asks about motives, a psychological phenomenon.

Nevertheless, what I can tell you is that no civilians were allowed to leave Soviet controlled areas either during the war or after it. I can also tell you that the Soviet Union was adamant that the US and Britain return all people, regardless of nationality, from Eastern Europe and they held American POWs hostage to this demand. I can also tell you that the Soviets systematically enslaved not just Germans, but all civilians in the occupied countries such as Poland, Hungary, Romania, etc. They would go through villages looking for any able-bodied men and arrest them and put them onto work crews. Many of these men and boys did not return home for years, or even just disappeared, and these were Poles, Hungarians, etc.

Does that answer your question?

No German prisoners captured by the Soviets outside the USSR were transported to the Soviet Union. In Poland, the Soviets discovered the extermination camp for humans in Auschwitz and in that place they organized war trials, of which a German officer (sorry I don't remember his name) was declared innocent of the charges against him. This officer remained a prisoner until the end of the war, but not as a war criminal.

However, those soldiers and officers who attacked the USSR, destroyed houses, palaces, cathedrals, massacred locals, set fire to villages, towns and cities, etc., and were captured on Soviet territory, all of them remained in the Soviet Union to restore what they destroyed.

Two separate periods

While WW2 was still ongoing, Soviets (naturally) wanted to destroy any German unit they could, by killing or capturing German soldiers. If evacuated these soldiers could continue fighting against USSR and Soviets wanted to prevent that. Note that Western Allies did the same, i.e. they continued attacking the Germans practically until the last day of the war. As for civilians, from Soviet perspective they were "resources" that could be used by Third Reich, both as source for military conscription (for example in Volkssturm) and as labor in industry and agriculture. Therefore, it was prudent to stop their evacuation too. Immediately after the war Soviets demanded handing over of all German POWs that fought on Eastern Front, as per Yalta agreement, and they would be used either as forced labor or put on trial for war crimes. It is possible that in their usual paranoia Soviets feared that Western Allies could switch sides and user remnants of Wehrmacht to fight USSR, such fears were not unfounded as latter Bundeswehr was created and manned by former Third Reich officers, and was primarily against USSR during Cold War.

Anyway, question what to do with German population remained after the war. Despite all the troubled history, Stalin preferred Poles to Germans. During Polish-Soviet war (1918-1921), Soviets lost lands in Western Ukraine and Belarus, east of Curzon Line. They reclaimed those lands in 1939 campaign, and naturally wanted to keep them. Since said territories still contained sizable Polish minority, Stalin decided to kill two birds with one stone. Eastern Prussia was emptied of Germans, annexed to Poland and populated with Poles from Ukraine and Belarus. This way, Stalin created population that was somewhat loyal to USSR and newly created socialist Poland - without them they would lose their newly gained homes. Similar mechanism happened in Czechoslovakia, Yugoslavia and other countries where expulsion of Germans happened - there were local winners of war spoils who naturally felt obliged to those who give them new property.

What about Germans ? Interestingly enough, while Stalin was alive (1953) there was no concentrated effort to keep Germans in Soviet occupation zone that would latter became East Germany . Reasons for that were various. Those more idealist hoped that socialist model of economy would prove itself superior, and that people would actually want to live there. More realistic noted that less population they had, less people they would need to feed in hungry post-war years. Stalin himself apparently proposed and hoped for united and neutral Germany, as a buffer state between East and West, therefore considering East Germany as only temporary solution. Only after his death, with East Germany firmly in socialist camp, efforts to keep population in as valuable resource were implemented. For example, Berlin Wall was built in 1961, and inner German border started to be fortified in 1952, but got final shape only from 1967.

Stalin pursued two separate objectives:

1. Establishing stable post-war borders which would reflect population ethnicity, which required extensive "population exchanges" - and those are cheaper to conduct when the populations to be exchanged flee on their own (cf. my answer to Why and how were east Brandenburg, Pomerania and Silesia taken away from Germany after WW2?)

2. Conquering as much resources (land, industrial and military equipment, infrastructure - and, yes, population, which can be put to work as either slaves or freemen) as possible.

So, when dealing with German population on the territories which were to be given to Russia or Poland, Stalin was brutal to make them flee. However, he wanted them to flee to Soviet-controlled Germany, not to the West, so those who tried to flee "too far" were stopped.

Another issue was that the traditional Russo-Soviet paranoia dictated that the Western allies would turn on the Soviets as soon as the Germans surrender, so letting able-bodies Germans fall into the Allied hands - where they could be armed and used against the Soviets - was to be prevented at all costs.

PS. Re: paranoia above: I am, of course, aware of the Operation Unthinkable, which, after all, was, at first, a plan to enforce the Yalta agreement WRT Poland which was blatantly violated by USSR, then a plan to defend against Soviet Army attacking the West. The main reason I call Stalin's fears paranoia is that he did not realize that only a totalitarian state can change overnight from denouncing Hitler to embracing him. The US and British public would not and could not stomach attacking the yesterday's ally.