For openSUSE Leap 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:arachnos/openSUSE_Leap_15.4/home:arachnos.repo
zypper refresh
zypper install lazarus-ide
For openSUSE Leap 15.3 ARM run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:arachnos/openSUSE_Leap_15.3_ARM/home:arachnos.repo
zypper refresh
zypper install lazarus-ide
For openSUSE Leap 15.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:arachnos/openSUSE_Leap_15.3/home:arachnos.repo
zypper refresh
zypper install lazarus-ide