Are you trying to fix a specific error message (like "MT67xx is not supported") or looking for a download link for a verified version?
(often by holding Volume Up/Down while plugging in the USB). sp flash tool support mt67xx verified
This is a classic authentication lock. You need an Auth file . Extract it from the stock ROM using "MTK Auth Bypass Tool v1.4" or use SP Flash Tool v5.2112 with "Disable Auth" checkbox enabled (if available). Are you trying to fix a specific error