I downloaded a game and it let me. but when I go to buy it'll probably grab my cc
Do you mean you want to use your credit/coupon rather than have your cc charged for the game?
In any case, it sounds like you're having trouble with the secure sign in for Big Fish, but not the initial sign in. Secure logins are a little different than regular logins. I checked Big Fish's help page, and besides the usual advice for making sure email and PW are correct, clearing the browser cache, and trying another browser, they advise this:
Trouble Signing in to Big Fish Account
If the issue persists, make sure that the date and time settings on your computer are correct:
1.Right click on the Time/Clock display in the bottom right corner of your screen, then select Adjust date/time.
2.Make sure that the date and time settings are configured to use your current date and time. Confirm that your Time Zone is set correctly and then click OK.
Big Fish also suggests checking out this page for more help: Trouble with Secured Logins Using IE
The Windows site offers more advanced troubleshooting, but I thought you might want to double-check your computer time and date--since that advice hadn't been suggested yet.