Legacy Account Age Verification Failure

If the linked EA account doesnt exist then you need to restore that account to be able to purchase

You can try to do this if the email hasn't been used on another account by attempting a password reset per this guide 
(note the comment about swtor accounts although if you can restore that deleted ea account it should be recoverable)

To protect your account information, only you can recover your account. It’s not something we can do for you.If you’re restoring a deleted account and haven’t created a new EA Account with the same email address as your deleted account, you may be able to restore your deleted account through a password reset. If you’ve created a new EA Account with the same email, you’ll need to change the email address on the new account first in order to reset the password for the deleted one.