For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:Astrophotography/openSUSE_Tumbleweed/Application:Astrophotography.repo
zypper refresh
zypper install phd2
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:Astrophotography/15.6/Application:Astrophotography.repo
zypper refresh
zypper install phd2
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Application:Astrophotography/15.5/Application:Astrophotography.repo
zypper refresh
zypper install phd2