FGU installation process still broken on Big Sur

Summary:
Installer is broken ; it proposes to "fix rights", can't do it, can't even tell what "rights" need "fixing" (, owner, group, POSIX, ACL ?)

Ruleset(s):
Can't even get there.

New Campaign / FGC Migrated Campaign:
Can't even get there.

Extensions/Themes:
Can't even get there.

Modules Loaded:
Can't even get there.

Operating System / Language Setting:
macOS 11.3, English

Steps to Reproduce:
Launching /Applications/SmiteWorks/Fantasy Grounds/FantasyGroundsUpdater.app doesn't dot anything visible.
/Applications/SmiteWorks/Fantasy Grounds/FGUpdaterEngine/FGUpdaterEngine.app failed at "fixing rights", without any useful information.

FIXED !

Method : randomly click buttons in app to force an update. Yeah !