For 15.7 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:andriinikitin:branches:openSUSE:infrastructure:MirrorCache/15.7/home:andriinikitin:branches:openSUSE:infrastructure:MirrorCache.repo
zypper refresh
zypper install MirrorCache
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:andriinikitin:branches:openSUSE:infrastructure:MirrorCache/15.6/home:andriinikitin:branches:openSUSE:infrastructure:MirrorCache.repo
zypper refresh
zypper install MirrorCache