It's a feature designed to stop theft, it wont be that easy to get around. If the Mi account really isn't yours then I would try contacting the seller in case it's their account used in testing the device before shipping.
Centerclockmod (separate mod zip) for 6.3.31 bricks MIUI on kenzo, just black screen after boot, reboot menu works but everything is black otherwise. Flashing disable zip fixes it again. Running on xiaomi,eu 6.3.31 ROM because the sMiui one wouldn't boot.