Welcome to the Forum!
A couple of Questions:
You have the same Behavior with Zorin 17?
Did You checked the Checksum?
Which Tool did You used to create the bootable USB Stick?
Are Secure Boot and Fast Boot in BIOS turned off?
Do You want to make a Dual Boot System?
Is Your BIOS in UEFI Mode or Legacy Mode?
Depending on that: Is the Partition Sheme of the bootable USB Stick GPT or MBR?
@romromillys Hi and welcome
to the forum.
Some more questions I'm afraid.
What is the make/model of PC and what graphics card do you have?
Did you ask for graphics drivers to be included at time of installation or not?
Nvidia ?
It would be more useful if you boot into Try Zorin from the install media then in a Terminal (Menu | Utilities | Terminal) enter:
sudo lshw -C video
and post back the results.