Be aware that ZorinOS devs are just two people, so please be patient awaiting support from them.
Please ensure you do a backup of all your personal files and also a means of re-installing macos before proceeding to install any second operating system alongside macos.
Have you had a look at this pre-insrallation advice, Before you install. It is primarily for PC, but expect would equally apply to Mac. Especially checking SHA256 checksum of the downloaded ZorinOS .iso.
When installing ZorinOS, did you use "Install alongside..." or the manual "Something Else" proceedure?