The parts numbers you need is available on the following site:
https://www.getbmwparts.com/v-2018-b...trim-rear-body
I have highlighted with redish circles the parts in the image below which you will need.
Assembly is like a puzzle, but let me know when you get stuck.
EDIT:
- All side panels are different. You will need the complete set. so 1 is include
- remove part 32 in second diagram its mounted behind the seats (there are two of them) it was used to to create hight for the spare will. Took me 20 minutes to figure this out.