Thunderbird beta install "blocked by group policy"

Windows 10 64-bit, Intel HD graphics. Updates applied.
Today Thunderbird crashes on startup. Same in safe mode.
Crash ID: bp-c342316d-01d4-4a1b-b615-2d84e0190517

Tried to install Beta version 67.0b3 (in Administrator mode) in order to disable graphic speedups but, after extracting, install fails with error:

7-zip / This program is blocked by group policy…

Same happens when trying to install 60.6.1 version.

I suspect this is related to 32/64-bit conflict. Any suggestions?

Thunderbird is packages as a self extracting zip file using 7-zip and has been for many years now. So I guess it is banned by your group policy.

However the crash you mention appears to be for version 60.6.1 and occurred 8 weeks after the version was installed.