Legal Question in Civil Litigation in Maryland

That depends entirely on your employer and whether or not you have the owner/lessee's permission.

Yes, it could well be trespassing to go onto another's property without their permission, even if one has legal access / permission to enter at other times. For instance, if an owner gives their neighbor permission to come into their house to water the houseplants while the owner is traveling in July, never gets the keys back and later goes away on another trip in September, the neighbor can't simply enter the house without specific permission to do so. In the same way, an employee may have access for certain purposes but not others.