For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:ardour/openSUSE_Slowroll/home:ecsos:ardour.repo
zypper refresh
zypper install fluidsynth
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:ardour/16.0/home:ecsos:ardour.repo
zypper refresh
zypper install fluidsynth
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:ardour/15.6/home:ecsos:ardour.repo
zypper refresh
zypper install fluidsynth