For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science:HPC/openSUSE_Factory/science:HPC.repo
zypper refresh
zypper install opa-fm
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science:HPC/15.6/science:HPC.repo
zypper refresh
zypper install opa-fm
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science:HPC/15.5/science:HPC.repo
zypper refresh
zypper install opa-fm