You’re entitled, usually required, to add your personal lock onto this when you start working on a locked out job, that way you can be confident they’ll come looking for the last guy to lock off the job before they can get running again, it may save your fingers/arm/life or job. Usually there’s a permit involved and you should know the conditions of the permit, or have your own permit to join a job.
You don’t need an apple account to use a Mac. If you just want to enter a username and set a password, that’s all you need to do. If you want everything synced between another Mac or iPhone and so on, sign into iCloud. But you don’t HAVE to, just skip it.