EDIT , March 19 , 2025 :
Rigid Audio site has reopened but user experiences so far has been varying.
Apparently then the IP has been sold and the site has got new owners. As part of that then people have to use PulseDownloader to download and install things. The app in itself IMO leaves something to be desired and e.g. at the moment do not discern between download location and install location since to the app it is the same.