Server Credits enable you to unlock the latest Samsung & LG phones by reading the unlock codes from the phone safely and quickly - without the need to root (void KNOX flag) and risk of bootloop. Just click Read Codes in the latest Z3x software.
Starting from 37 version of Samsung tool to repair IMEI and some other operations with phones you need to have an account with credits on it, to can authorize on the server. The number of credits in the account does not matter. It’s free, credits will not be charged.
Without this, you won't be able to use the new solution.
Read some details about credits