For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:j-engel/openSUSE_Tumbleweed/home:j-engel.repo
zypper refresh
zypper install freeradius-server
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:j-engel/16.0/home:j-engel.repo
zypper refresh
zypper install freeradius-server
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:j-engel/15.6/home:j-engel.repo
zypper refresh
zypper install freeradius-server
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:j-engel/15.5/home:j-engel.repo
zypper refresh
zypper install freeradius-server