We need to enter the BIOS/UEFI of your system to change a few settings. Most BIOS/UEFI systems use a special key that lets you choose the boot medium, and that lets you choose the BIOS configuration screen (where you can select the boot order). Depending on the BIOS, these keys are: Esc, F1, F2, F8, F10, F11, F12, or Delete. Usually, this information is briefly displayed during boot
Once you're in the BIOS/UEFI screen you need to find secure boot and turn it off.
You need to set your USB key as the first option to boot from
If everything went correctly you should see the RebornOS boot screen
Select NVIDIA if you have an NVIDIA graphics card or select boot install medium if you don't!