For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:RemoteDesktop/openSUSE_Tumbleweed/X11:RemoteDesktop.repo
zypper refresh
zypper install rustdesk-server
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:RemoteDesktop/15.6/X11:RemoteDesktop.repo
zypper refresh
zypper install rustdesk-server
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:RemoteDesktop/15.5/X11:RemoteDesktop.repo
zypper refresh
zypper install rustdesk-server