This is a try to transfer my Question from (google groups/read only) to here:
I have files in the cloud and I can access them in Windows and in Linux via netdrives.
That works for Libreoffice text files in Windows and in Linux.
With TiddlyDesktop in Windows I can access my cloud TiddlyWikis and edit them.
TiddlyDesktop in Linxux can handle my local TiddlyWikis but If I try to access cloud TiddlyWikis (the same which work in Windows) then I get an error message that caja cannot handle this. Does anybody know how to solve this problem.
In google groups I got this answer from jerojasro:
did you install TiddlyDesktop using flatpak? or using apt?
If you installed it using flatpak (it seems it’s called FlatHub in Linux Mint), perhaps you have a permissions issue; I suggest you check https://forums.linuxmint.com/viewtopic.php?t=334350 or How to manage Flatpak permissions with Flatseal | TechRepublic for ideas of things to test to try to fix your issue.
Thanks for this answer. I even managed anyhow to see flatseal working but since I am just an end user (really!) I do not know what to do with all the possible permissions.