Install firefox extension

i notice when i enable the two browser extension for ff and chrome in install extras the ff task always fails according to the little log window that pops up:

Funny thing is it is already installed, same in chrome.
But when removing it, i get the similar message instead of it being reinstalled.
Did i do any misconfiguration maybe that causes this?
How can i find out, what causes this?

Thanks in advance.

Which version of Firefox do you use on which version of macOS? The extensions are also available via this page:

mac OS 10.15.7 and FF 78.8.0esr 64bit.
I know as mentioned the extension is already installed.
Somehow it is not recognized. And when removing it also does not change the message.
Then reinstalled manually using that source page you mentioned.
While for Chrome there is no message, so it seems to notice that is is installed already and does not perform anything.


PS: read in a total different topic that access rights of the DT application to the system has to be set right, but then in would also expect chrome to fail if that would be the reason?