Giving ur info for 21tokens is not worth it.. no mater where it is or what they use.
Checking Top Eleven - Be a Football (Soccer) Manager now and i can see some pretty good offers about installing games on ur phone/tablet and the rewards are awesome.
19tokens for installing a game..
beside that you pay them 1$ and wait 7 days to get them back.. 21tokens probabbly worth about 1.5-2$. i don't see how thats a good offer.
If you'r doing it then go with paypal, atleast its 101% safe.
but not Credit card