Back in 2021 I was able the first time to archive a project, but last week not anymore.
Even though the settings in Security & Privacy are stil the same as well the access permissions
of the (new) target folder ()
I remembered that after a Catalina security update, the Wacom-tabled did not work anymore and it had to be reinstalled with a new Wacom driver. But had no idea if this fact was relevant for the actual situation.
Surprisingly nevertheless of the error message “Archive or Library is read only” , Flame was able to write/export two/2 files to the target folder.
In the following thread, its recommended to give DLmpd as well Fulldisk Access, so I tried this as well and voila it did work 
Caching: 2020.3 with Backburner 2021.0.0 on Catalina - Logik Forums
But now it becomes even more funny, after removing Fulldisk Access for DLmpd, Archiving is still working properly. Really don’t know whats going on …
PS
I do know that its time to update the macOS and Flame, but I know as well that sometimes it’s adviseable not to touch a running system
PS 2:
In other threads it’s recommended to activate “ignore permissions”, but I was unable to find this option.