From the basic installation page: https://docs.projectquay.io/deploy_quay.html "For a Project Quay Registry installation (appropriate for non-production purposes), you need one system (physical or virtual machine) that has the following attributes: Red Hat Enterprise Linux (RHEL): Obtain the latest Red Hat Enterprise Linux server media from the Downloads page and follow instructions from the Red Hat Enterprise Linux…
The RHEL version linked is 7.5, not 8.1. They might just forget to update the doc.
So guessing the docs will slowly shift to RHEL8 and podman.