RHEL8 Installation source from USB

I have an installation setup which includes one USB with RHEL8.4 ISO and then a separate USB with a ks.cfg kickstart file. It boots up into the installation and I use the boot option 'linux inst.ks=hd:LABEL=KS_USB:/ks.cfg. It proceeds with the installation and correctly fills in all of the information besides the installation source with 'Error setting up base repository'.

How do I point to the USB with the ISO for the BaseOS and AppStream?