Everytime i use my ufi donggle to flash using auth always end up with errors

MEGADETH

Everytime i use my ufi donggle to flash using auth always end up with errors,
ERROR: Only nop and sig tag can be recevied before authentication.
ERROR: Only nop and sig tag can be recevied before authentication.
ERROR: Only nop and sig tag can be recevied before authentication.

[SERVER] Sorry, We have run out of all available slots, please try again in 2 hours.

i've been waiting for 2 hours and nothing changes, same error with more long time to wait.
i know its mean to flash device we need to pay using ufi credit, i have enough credit. Please, can anyone help?