The modern way is [Roku, blu-ray, satellite, etc.] -- HDMI cables --> AVReceiver --> TV and Speakers.
If the receiver is an audio-only device and you have a modern Roku, then you will probably have to kludge something up, involving an HDMI audio extractor. (There were some rokus in the past that had multiple cables going out for older equipment, but none of them are sold currently, and possibly none of them are still supported.)
I wouldn’t expect Roku support to have any clue about anything like that, but if you really want to, you can contact them here: https://support.roku.com/contactus
Banned but back. Because why not?