It’s probably canceled automatically because you didn’t/couldn’t do the verification.
Are you registered on Gameflip using the regular email/password login? Make sure you have verified that email address https://gameflip.com/settings
The PayPal verification email title should be “Confirm your Gameflip purchase”, in it is a link to complete the verification.
If you still can’t get that email then you can try adding the funds again, and contact support so they can manually verify you.