For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:R:released/openSUSE_Tumbleweed/devel:languages:R:released.repo
zypper refresh
zypper install rstudio
For openSUSE Factory ARM run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:R:released/openSUSE_Factory_ARM/devel:languages:R:released.repo
zypper refresh
zypper install rstudio
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:R:released/15.5/devel:languages:R:released.repo
zypper refresh
zypper install rstudio