For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Max1:branches:devel:openSUSE:Factory:Apps/openSUSE_Tumbleweed/home:Max1:branches:devel:openSUSE:Factory:Apps.repo
zypper refresh
zypper install rednotebook
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Max1:branches:devel:openSUSE:Factory:Apps/15.4/home:Max1:branches:devel:openSUSE:Factory:Apps.repo
zypper refresh
zypper install rednotebook