For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:340.108/openSUSE_Tumbleweed/home:Bumblebee-Project:nVidia:340.108.repo
zypper refresh
zypper install dkms
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:340.108/15.5/home:Bumblebee-Project:nVidia:340.108.repo
zypper refresh
zypper install dkms
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Bumblebee-Project:nVidia:340.108/15.4/home:Bumblebee-Project:nVidia:340.108.repo
zypper refresh
zypper install dkms