Hi there everyone!
I've been using ZorinOS for quite a while now on my laptop without any issues whatsoever - and I love it! That's why I decided to install it on my Desktop too now!
I was running Windows 10 up until now on my Desktop. I plugged in my Zorin USB drive, booted from it (selected "Try or install ZorinOS (modern NVIDIA graphics)" and it worked! Both of my monitors got detected, I could configure them in the NVIDIA Settings app and everything was fully functional. So I started the installation process: I have a SSD Boot drive and a HDD for file storage, so I decreased the size of the Windows partition on the SSD and created a new one for Zorin (so I can dual-boot). The installation process completed successfully, I rebooted and completed the last step ("remove the installation USB drive and hit enter"). It booted, I saw the grub menu where I could choose between Zorin or Windows, and after selecting Zorin, my screen went black. The fans suddenly started spinning loudly, and after ~ 30secs it got quieter, but the screen was still black (no cursor, no text, nothing). I waited for over half an hour, but nothing happened (the monitor did not go to standby).
Anyway, I tried rebooting a few times, but I always got the black screen. However, when I selected to boot into ZorinOS in Recovery mode in the grub menu and selected "resume", I got into Zorin and everything worked perfectly. The NVIDIA drivers loaded and everything was fine... I checked the boot logs and a few other things, but couldn't find the cause for the black screen.
I tried booting into "normal" Zorin a few more times and tried to follow different suggestions I found in this forum regarding similar issues (like setting "nomodeset" in the grub boot config and a few other things) - but nothing I tried fixed it.
I even went ahead and completely reinstalled Zorin, but it didn't help. Manually re-installing the NVIDIA driver didn't help either... I also tried disabling Fast boot in my BIOS, which also didn't help (secure boot was already disabled).
Booting into Windows still works perfectly, so there is no hardware error with the graphics card... I'm trying to get Zorin to work now for 3 days and I'm kinda desperate.
I have an Intel Core i9-10850K CPU, 32GB RAM and an NVIDIA GeForce RTX 3060 - I guess this should be more then enough to meet the minimum system requirements 
I am grateful for any help as I'm finally trying to switch my last non-ZorinOS device to Zorin too 
Thank you very much!