Can't run Hybrid on MacOS 15

[nomad]

Hi there,
and thanks for your efforts.

Unfortunately, I can't install Hybrid on a Mac under Sequoia 15.8.1.
Yes, I know it's not notarised, but if I go for Privacy and Security, it doesn't show up. 
Usually, after having tried to open it directly and hitting Cancel, one should be able to allow it there.

What to do?

TIA