ADE 2.0 does not open 'older' ACSM files

I found many questions/help requests re opening ACSM files -- but none like this.

I have a number of ACSM files that are several years old and I no longer have data re where/how they were obtained.  I recently lost the 'My Digital Editions' folder but did have the ACSM files backedup.

I installed ADE 2.0 and it works fine with ebooks downloaded from Adobe.  However it will not open any of the ACSM files that I had saved.  Each gives the error:

"Unable to download. Error getting license. License server. E_ADEPT_NO_TOKEN."

Can anyone help me understand what the error means and/or how to corect the situation so I can retrieve my ebooks?