After installation. There is no Grub Menu. GNU Grub minimal Bash

[zabadabadoo]

I assume you have been searching the internet for answers:
Here is one re Ubuntu which should also be good for Zorin.

How to make grub menu appear instead grub minimal bash-like in booting?

Question: From live USB, did you install direct or use the "something else" method?
See this:

Partitioning during installation

Once you choose "Something else" installation option, it will take you to the partition screen. Use “-” button on that screen to delete partitions and “+” button to create them. Delete the existing Windows partitions (unless installing alongside Windows) and then create root (/), swap, home (/home), and ESP/EFI (50 MB). ESP/EFI depends on if you have UEFI turned on in your BIOS, otherwise you don’t need it (the installer will tell you if you need it). If you have multiple drives, please make su…

Which flavour of Zorin are you installing, Core or Lite etc.