NVIDIA graphics drivers on Zorin 18 Pro

If secure boot and fast boot in your BIOS are turned on, turn them off (or create a MOK for use with secure boot enabled) and if you have a Dualboot with Windows, also turn off fast startup in Windows.
When you have a up-to-date hardware you could also test a later kernel for better hardware support, e.g. mainline or liquorix.

You can also send a help request to the Zorin team