Thanks but when I run gpg --keyserver pgp.mit.edu --recv-keys E9A491A3DE247814E7E067EAE06F8ECDD651FF2E
or sudo rpm-ostree install https://mirrors.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://mirrors.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm
I get the following error messages (for the first command): gpg: keyserver receive failed: No data gpg: keyserver receive failed: No keyserver available
or (for the second command) error: Updating rpm-md repo 'rpmfusion-nonfree': Failed to download gpg key for repo 'rpmfusion-nonfree': Curl error (37): Couldn't read a file:// file for file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmfusion-nonfree-fedora-33 [Couldn't open file /etc/pki/rpm-gpg/RPM-GPG-KEY-rpmfusion-nonfree-fedora-33]