Whenever I see that error message it's usually because I also have the database open in Access itself and I have done something that has essentially "locked" the database, like opening an object in Design View or having made changes to a VBA module. Make sure that you have no open instances of the Access application itself and try again.
Another possible cause is that the root folder of some drives can have restricted permissions. You could try moving the .accdb file to a location where all users normally have read/write access, e.g.,
C:\Users\Public\Documents
and see if that helps.