how to remove device lock not knowing either options but knowing the knock code?

[AC Question]

I know my knock code but someone ended up getting my device locked, theyre asking for a Backup PIN, which I Dont know what it is (can someone pls explain), and an account unlock which i forgot the password to. Im not getting any "forgot my password" options and im not in any way willing to reset the phone since it has all my work and such. Is the account unlock password same as my gmail pass? if so it keeps refusing it.