For anyone on Fedora 36 wanting to play with Ardour 6.9.0 with some awesome free effects and synth plugins, try this:

  sudo dnf install ardour6 lv2-calf-plugins-gui ladspa-autotalent-plugins lsp-plugins-lv2 lv2-zam-plugins lv2-synthv1 lv2-amsynth-plugin

All the plugins will automatically show up in the plugin manager!