Kodi 18: use 'master' branch: https://github.com/maxbambi/plugin.video.raitv/archive/master.zip
Note: Kodi 18 version of plugin is not fully supported. I have tried to merge new fixes also in this version, but something could not work well
Kodi 19 - 20: use 'matrix' branch: https://github.com/maxbambi/plugin.video.raitv/archive/matrix.zip