E-License and Adobe ID

I want to read ePub files from my library in ADE.

I download eBooks from the neighborhood library using my library card number as the ID.

The ePub comes first as an ascm file. It defaults to OverDrive, another reading app.

I can't change the program that opens it. ADE doesn't appear, even though I have the program.

When I open ADE and try to adjust the authorization, it only gives me the option to enter my Adobe ID or cancel my authorization and lose previous ePubs. Since the e-license is through my local library card, I want to add that option. I don't want to erase the Adobe ID authorization. I just want to add the library ID option so I can read those books as well.

Thanks for any help or advice.

Am using Windows 8.1

Message was edited by: Christine EDIT: I am trying to download the PDF book files, just to be clear.