How to properly configure edit permissions for other/guest accounts?

I have this issue on both of the docker versions (amd&ARM).

I have given (as far as I know) all the needed

permissions to let other or guest accounts edit files I shared with them

but the changes they make are never saved.

This handicaps my FileSharingSystem a bit, as I am unable to collaborate with other people...

Can someone maybe go through all the settings with me to double-check?

Thanks in advance!