Can't Download Crankk unto miner

Got some used Heltec miners , found out still active on helium . Also found that firmware was 2019 . Can I flash Crankk onto miners ?. Will the miners accept me as owner ? Or will last owner have to transfer miner over . Then I can install Crankk . I have tried going by guides but it crashes , also using a Mac mini not a pc based computer . What is USB - C on back of Heltec used for can I download that way to Crankk. Please help