When I try to download an epub (with DRM) directly on Ipad with an app that uses Adobe ID (overdrive, bluefire), it doesn't open because the app sees it as a PDF file. I decided to try downloading it in my dropbox app and I then realized that the file name as a pdf extension next to the acsm extension (hence the app thinking it's a pdf file). So the file will be something like this "blabla.acsm.pdf". If I go through dropbox and delete the pdf part, the file will then open in bluefire from dropbox without problem. It's just that I find it's an unnecessary hassle to have to go through all those steps. Is there a reason why there would be a pdf extension on my acsm file? Is there an other way to open it directly in an app?
I would suggest contacting the store that you purchased the ebook from. They should not be handing out ACSM files that have a PDF or EPUB extension after them. Most ebook reading applications check the file extension and mime type to determine if they can handle the file you are passing to them (which is why bluefire/overdrive do not open this file for you unless you remove the extension). Ebook reading applications in this case, are only expecting ACSM extensions and the store you purchased from is not following conventions of the ecosystem.