Thanks @AlexProgrammerDE here it is:
@roj ok thats weird. Everything should work. Can you restart the container and give me the first logs you get?
@roj can you just give me the download of the logs?
@roj hmmmm. Can you try to manually put the paper.jar on the Pi?
@AlexProgrammerDE Can you please explain how to do that?
@roj oh no. Sorry for the really late answer. Download the latest build: https://papermc.io/downloads Then connect to the Pi as described in the blog post and then replace the paper.jar file with the file you just downloaded. Make sure the file name of both is paper.jar