For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:dl8fcl:afu/openSUSE_Tumbleweed/home:dl8fcl:afu.repo
zypper refresh
zypper install fldigi
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:dl8fcl:afu/15.6/home:dl8fcl:afu.repo
zypper refresh
zypper install fldigi
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:dl8fcl:afu/15.5/home:dl8fcl:afu.repo
zypper refresh
zypper install fldigi