I think that your issue is addressed by this post:
The Denon AVR is not yet Roon Ready - but it may be at some point in the future - but you will not get any timeframes from Roon because:
- It is not their policy to give such timeframes
- it is not always something that Roon can control
In the meantime, you may have other options. Does your Denon AVR offer either Chromecast audio or Airplay connectivity? If so you should see those endpoints appearing in Roon → Settings → Audio (but not in the Roon Ready section).
If Airplay and Chromecast Audio are not available, you should be able to connect your AVR to a streamer or a small computer running Roon Bridge (or even to your Roon Server if co-located) using SP/DIF over either COAX or Toslink connectors (which will most likely give you a Stereo only presentation - no multi-channel) or HDMI which, depending upon the nature of the source, could give you multi-channel.