Actually it might be too large if the file itself is about 50 MB... you have a total of 50 MB of space available in your account, and you are using about 3 MB of that space already. So if the file is over 47 MB it's just a bit too large to fit in your current limits.
You can increase your limits now by upgrading your subscription, and you won't need to pay anything extra this month if you do so.