On what N(th) day of the week did Jesus die according to the Adventist?

It is easy to find the correspondance between the Nth day of the week (as written in the Bible) with our days of the week. We gave the name "Sunday" to the Biblical first day of the week, Monday to the second, Saturday to the 7th etc.

There are a couple of things that make it more complex. One is that the Biblical days ran from one evening to another, not from midnight to midnight. So if something happened at 9pm on Friday (in our time reckoning) that would be Saturday (7th day) in the Biblical way of working.

The second complexity is that some societies changed the way they numbered the days. For example Europeans often started calling Sunday the 7th day and Monday the first day. But this is an invention of middle-age Europeans, centuries after Christ, and not anything to do with the Biblical numbering.

However in terms of the crucifixion the numbering is very easy. The resurrection appearances are clearly described in the Bible as being "on the first day of the week", and the crucifixion as being the day before the sabbath, i.e. the sixth day. Since both these events happened before evening, they occurred on Sunday and Friday respectively.

Here’s a quote from one of the most authoritative Seventh-day Adventist sources you can find.

On the sixth day of the week they had seen their Master die. - Ellen White, Desire of Ages, page 794

And as already pointed out, this matches the Bible account that Jesus was crucified on the day before the Sabbath, which Seventh-day Adventists believe is the 7th day.

Here’s a short timeline:

• 6th day - Jesus was crucified, died, and was buried. (Note: they did not wait until the next day to bury Him.)
• 7th day - He rested in the tomb.
• 1st day - He rose from the dead.

Here are more Seventh-day Adventist sources:

It was not by chance that the Saviour was crucified upon Friday, the sixth day of the week. - SN Haskell, The Cross and its Shadow, page 97

We know that the Saviour was crucified “the day before the Sabbath.” Mark 15:42. We know that the Sabbath was “the Sabbath day according to the commandment” (Luke 23:54-56), and that was the seventh day—Saturday—and therefore “the day before,” was the sixth day—Friday. - AT Jones, Signs of the Times, March 11, 1886

The quote here, doesn't reflect the views of many Adventists. It should be noted that many reject the teachings of Ellen White who plagiarized the work of someone else. "We know that the Saviour was crucified “the day before the Sabbath.” Mark 15:42. We know that the Sabbath was “the Sabbath day according to the commandment” (Luke 23:54-56), and that was the seventh day—Saturday—and therefore “the day before,” was the sixth day—Friday. - AT Jones, Signs of the Times, March 11, 1886". This is the exact same mistake made by the Catholic church. They don't understand Jewish culture, or Jewish feasts, or the Hebrew calendar.
Scripture is clear that there were two Sabbaths that week. In Hebrew, Shabbat is the weekly sabbath, and the feasts are also Shabbat.
So people see that Christ was crucified the day before the Sabbath - and they think weekly sabbath - so the day before would be Friday. But Feast of Unleavened Bread is a high Sabbath - no work can be done and buying and selling is forbidden. Passover is Nisan 14th - and the day of preparation for Unleavened Bread. Nisan 15th. "After the Sabbaths" [plural] the women bought spices. Weekly sabbath is Sunset Friday to Sunset Saturday. - Think about it. It's impossible to go buy spices after sunset Saturday. In the first century - The only light after sunset is candles. Your question is quite confusing and not clear - but I'll try to use your number of week day- not names of day, **But we have to remember that Hebrew day is Sunset to Sunset.

• Jesus Crucified 4th day- afternoon- Passover.
• 5th day is high Shabbat/sabbath Feast of Unleavened Bread. No work, no buying. Women rest.
• 6th day women buy spices - prepare for weekly sabbath.
• 7th Day - weekly sabbath - no work allowed, no buying allowed. 2nd Sabbath of Holy Week.
• it's twilight, just after sunset - first day of the week starts. Sunday - Women are so anxious, and rush to the tomb, as soon as they can- after sunset. Arrive at the tomb, still dark. Saturday evening - Jesus is already risen. Christ crucified day 4 - afternoon. In the tomb, day 5,6,7, [3 days and 3 nights, just like scripture says in Jonah, and just like Christ himself said - 3 days and 3 nights in the heart of the earth.
  On day 1 - Women arrive - Jesus had already risen.