Для openSUSE Factory запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/Archiving/openSUSE_Factory/Archiving.repo
zypper refresh
zypper install stuffit
Для 16.0 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/Archiving/16.0/Archiving.repo
zypper refresh
zypper install stuffit
Для 15.6 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/Archiving/15.6/Archiving.repo
zypper refresh
zypper install stuffit