Allow users to moves files into a "readonly" directory

I am on Ubuntu 20.04 and I have users who work on Jupyter notebooks in their own home directories, and then they can move the notebook onto a shared directory on the Jupyter server where everyone can read them, but not edit or delete them. Only the owner should be able to delete and edit. I tried to work with the setgid and sticky bits, and the last issue I have is that if the file has 664 permissions, I don't see a way to change it to 644 so only the owner can change it.