For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mauriziogalli/openSUSE_Tumbleweed/home:mauriziogalli.repo
zypper refresh
zypper install plank-reloaded
For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mauriziogalli/openSUSE_Slowroll/home:mauriziogalli.repo
zypper refresh
zypper install plank-reloaded
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mauriziogalli/15.6/home:mauriziogalli.repo
zypper refresh
zypper install plank-reloaded