I think 1 first deposit for every 50 click-through’s would be a very aggressive goal, and way too aggressive for GoClick traffic. When I used GoClick, I saw conversions of more like 1 first deposit for every 200 click-through’s or so.
As far as ratio of downloads to deposits goes, I’d double-check with the program about how they count “downloads”. Sometimes your number of downloads is artificially inflated.