I am a GSuite user and a ZTE Axon 7 device that I recently sold via SWAPPA was setup with Android Device Manager. I did a factory reset on the device, but when the buyer powered on the device, he said that the device indicated that it was already associated with a Google account and he would need the credentials to configure it. I went into the standard Find my Device and tried to remove it, and it appeared to have been removed from whatever screen I was on, but the buyer is still complaining. I am still seeing the device here: https://www.google.com/android/find I wondered if GSuite's device management might be at play, and just went there to "delete" it. Am wondering what else I can do?
To be honest, there isnt much more you can do, I wrestled with google for a week straight and still nothing. The FRP lock on most ZTE devices can be easily bypassed by watching YouTube videos. If the buyer isnt tech savvy, I would suggest a online shop that can FRP unlock the device remotely. In the past I've used a site called unlockjunky, but there's tons of them out there.
An answer that works... Give him your email and password to unlock the device. Once they are in and working, change your password.
Yes, it has potential risks, but 99.99% of the time this would work out just fine.