The first argument of the command is the cells binary itself. So if you want to use ./cells admin user-unlock -u "LOGIN" you have to be in the same folder where the binary is.
You were nearly there: you just have to replace “LOGIN” by the real login of the user you want to reset, for instance, if you log with a user admin in your adminstrator account, you should use:
Lmao, crap. I had done it both ways with the same error. I guess I just didn’t screenshot it that way. I feel like an idiot for sending that lol. Either way, same issue. Know what it could be?