you have to get a job at the muesam to get it.
you can with the key!
you finish getting your job and when you finish he gives it to you
with the supply room key
To get into the Supply Room You have to get the Key from The Person who hires you
In the supply room
If you have entered it from the tunnel system then you can exit it the same way. if you have entered it from the door you can use the door. if you need to get into the supply room you have to get a job first which means you have to talk to the assistant curator. once you get the job he will give you a key to the supply room. i hope your question was about counterfeit island. also i hope this helped.
finish the tests and he will give u a key.
Don't ask me, o_o.
the security guard in the security room gives it to you
If your talking about Counterfeit Island then you get the key and go back to the museum on Counterfeit Island
get the key!
Apply for the job with the assistant curator and when you pass the Forgery Detection class, he will give you a key to the Supply Room.