Unable to add remote

Tried adding the remote as prescribed in the README, but it doesn't seem to work:

$ flatpak remote-add --no-gpg-verify ubports https://gitlab.com/ubports/core/flatpak/ubuntu-touch-flatpak-runtime/-/jobs/artifacts/master/raw/repo/?job=apps
error: Remote listing for ubports not available; server has no summary file. Check the URL passed to remote-add was valid.

I'm guessing it's due to this CI failure: https://gitlab.com/ubports/development/core/flatpak/ubuntu-touch-flatpak-runtime/-/jobs/8780559922