CONTENTdm has legacy user names like CDM\12345admin and 1234user01 that no longer are managed for password resets.
Please create new user accounts and add them to CONTENTdm following the Add a new user documentation.
Once you have the user name registered contact OCLC Support and provide the user name you will need to be added to the CONTENTdm Server Administration so you may sign in.