It works in OBS fine, for the most part.
If you are on a single PC setup and streaming PC games, it will likely be of no benefit to you. OBS already has the most efficient methods of capturing available internally. You will still do all encoding within OBS, not with the AVerMedia encoder (not that you would want to, the quality of that hardware encoder is really awful) so your PC will still assume the load of your CPU doing the real time encoding.
Now, if you were to build a second PC for dedicated encoding, then you would use that capture card to accept the feed from your gaming PC and have the dedicated encoder's CPU do all the encoding. This is done by many people to completely eliminate the load of streaming.