For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:390.157/openSUSE_Tumbleweed/home:Bumblebee-Project:nVidia:390.157.repo
zypper refresh
zypper install dkms-nvidia
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:390.157/15.6/home:Bumblebee-Project:nVidia:390.157.repo
zypper refresh
zypper install dkms-nvidia
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:390.157/15.5/home:Bumblebee-Project:nVidia:390.157.repo
zypper refresh
zypper install dkms-nvidia
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:390.157/15.4/home:Bumblebee-Project:nVidia:390.157.repo
zypper refresh
zypper install dkms-nvidia