After a cursory browse with
JetBrains DotPeek it seems the program does nothing malicious however do not take this as an endorsement nor a guarantee.
The software appears to have a hard-coded username/password as mentioned which is admin/12345 and moves files in/out of a hidden folder to facilitate lock/unlock.
Which would mean the file could easily be updated(the exe) with malicious code at any point in time.