1. Go to:

http://www.acapela-nvda.com/

2. Follow the instructions, and get to:

http://www.acapela-nvda.com/get-your-download-here-v1-7/

3. Download the engine. I saved it.

4. Download the addon with all of the calibri voices or whatever they're called. Again, I saved it.

5. Go to where you saved them. Click on the addon for the engine. Tell it to install. Say no when it asks you to restart.

6. Then click on the addon with all of the voices. Again, say yes you want to install it. This time, restart.

7. Hit NVDA-ctrl-s, pick a capela as your synth.

For me, this talks just fine. I don't know that I'd buy them, because I've never been a huge fan of their voices and there's no rate boost that I can see, which means even at a hundred percent, it's slower than the rate I usually read at. But I am absolutely running NVDA 2021.2, I just checked, Windows 10 21H1 with latest updates, and it's working just fine. I didn't even get anything about picking a trial license or whatever, I just did the above steps, and it's working, for how long, I have no idea, not that it matters because I'm going to uninstall it all after I'm done writing this message anyway. I think I did briefly do a trial a few years ago, so maybe it's just picking up on that, although I don't know if I did it on this machine or not. Anyway, working just fine here.