Good question!
To open the acsm file and read your book, you will need Adobe Digital Editions, as well as a free, personal Adobe ID, which can be created as Adobe Digital Editions is installed. Adobe Digital Editions a free program that is different than Adobe Reader. (ADE is also in the Apple App Store and Google Play.)
It is possible to download and read books in Adobe Digital Editions when authorized without an Adobe ID, but you can only use books on multiple devices if you have both devices authorized to the same Adobe ID. You can activate up to six computers and devices per ID. If you authorize ADE without an Adobe ID, any books downloaded will be limited to that single device.
To create an Adobe account if you do not have one:
- Go to accounts.adobe.com
- Click “Get an Adobe ID”
- Fill out the form
- Click “Sign Up”
Your Adobe ID will be the email address you used to sign up.
To authorize Adobe Digital Editions:
- If not prompted to authorize when you first open ADE, Go to Help > Authorize Computer
- You will be asked to select an eBook Vendor - select Adobe ID
- Enter your newly-created Adobe ID and Password and Select "Authorize" or if you only want to access it on the single pc, check the "I want to authorize my computer without and ID" box and Select "Authorize"
Next time, if you already have Adobe Digital Editions open before downloading, we find this makes the "handoff" between the publisher / vendor platform and ADE easier.
Adobe offers some trouble shooting help as well: