Most likely due to previous Zentyal (3.3.4) installation that was not totally removed.
Performed clean-up and install again, only zentyal-core.
It works better, meaning installation proceeds and prompt you for "Zentyal HTTPS port".
This is slightly misleading because what you define here is not HTTPS port but Zentyal
admin port. But once you know it, this is not a major problem
I set it up with my preferred admin port and try to connect but... nothing. It doesn't work because Zentyal admin is still listening on port 443.
However, if you look at processes that are listening, you will notice that nginx is listening on port 6xxxx, "xxxx" being what you have defined as your preferred Zentyal admin port...
Once connected to port 443, you can change it using GUI
Testing further