For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/multimedia:proaudio/openSUSE_Tumbleweed/multimedia:proaudio.repo
zypper refresh
zypper install rosegarden
For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/multimedia:proaudio/openSUSE_Slowroll/multimedia:proaudio.repo
zypper refresh
zypper install rosegarden
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/multimedia:proaudio/15.6/multimedia:proaudio.repo
zypper refresh
zypper install rosegarden
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/multimedia:proaudio/15.5/multimedia:proaudio.repo
zypper refresh
zypper install rosegarden