Installer doesn't load on older iMac

I want to install RHEL in kiosk mode on an ageing Apple iMac, but as soon as I select the USB device the system hangs. I can boot it successfully on other systems so there's no problem with the USB image or stick. Fedora 35 Workstation is currently on this system so I'm not sure if it's just RHEL that doesn't support it. I saw in another post someone pointed out that the newer M1 chips use a smaller page size which prevents RHEL from loading and thought this might be a similar issue, but I don't know.

Have you been able to load RHEL on a Mac?