I can get beta updates through Steam, but with a license it seems to have to have both the Free edition and Personal edition in the Steam library and have both set to use beta updates. The dropdown box for choosing beta is also glitchy and sometimes you have to close the dialog and reopen it to choose it. Both are problems with Steam, so we can't fix them I'm afraid, you might want to try contacting Valve. We do release beta updates simultaneously with Steam, and from what I've seen they usually come down to the actual Steam client within 30 minutes.