well, you probably shouldn't run that specific mask.... and probably you shouldn't run a mask attack (see https://hashcat.net/wiki/?id=mask_attack , -a 3 ) at all for itunes backups.
I would suggest starting with a dictionary attack (-a 0) or dictionary attack with rules (-a 0 -r, see https://hashcat.net/wiki/doku.php?id=rule_based_attack and the rules/ folder in the hashcat directory, e.g. hashcat -m 14800 -w 3 -a 0 -r rules/best64.rule hash.txt rockyou.txt)
I also would suggest to try remember as much as possible from the password and make your attack more clever and targetted depending on how much you remember/know about your password.
Good luck
(btw the above command posted by you - the test if everything is working - with -a 3 ?a only tries a one-length-only character password, alphanumberic with symbols a-zA-Z0-9 + !" #$%%&'()*+,-./:;<=>?@[\]^_`{|}~)
I would suggest starting with a dictionary attack (-a 0) or dictionary attack with rules (-a 0 -r, see https://hashcat.net/wiki/doku.php?id=rule_based_attack and the rules/ folder in the hashcat directory, e.g. hashcat -m 14800 -w 3 -a 0 -r rules/best64.rule hash.txt rockyou.txt)
I also would suggest to try remember as much as possible from the password and make your attack more clever and targetted depending on how much you remember/know about your password.
Good luck
(btw the above command posted by you - the test if everything is working - with -a 3 ?a only tries a one-length-only character password, alphanumberic with symbols a-zA-Z0-9 + !" #$%%&'()*+,-./:;<=>?@[\]^_`{|}~)