Below is a suggestion that might be helpful (You only need access to one AP)
1) Power off all of these new 345 APs.
2) Remove one of them and login to it and configure it as a preferred master in the Instant cluster. The serial number is available on the AP itself which you will use as the password.
3) Power on the other 345 APs..They will boot up and join this cluster.
4) Once all the APs are in cluster, convert them to a controller based APs