Forgot email and password, Frp locked

[willsp28]

i have a old phone, And i dont remember what email i used, i have managed to get back in, but it won't let me add any gmail accounts, ive got test dpc but it sais this app is not the owner of this device, but i added it in security device administrator, isn't that the same thing, when i try to set up a new account it says, this device is locked by factory reset protection, contact your it department 

 

[willsp28]

It is a zte but i dont remember the exact model