The website has a link to the book, which is stored in a folder on the site's server. The HTML code is <a href="eBooks/Assignment-10-12.epub">.
I'm tapping the link and the browser app is opening the file as a text file (I'm assuming it's the browser app that is opening the file as text). The file is starting off with the ePUB file header string.
According to the Aldiko website, at least the Aldiko app should present me with an option to open the book in Aldiko, but that's never showing up. I have not tried saving the text file to the SD card (I'm not sure how to do that, but hopefully, once the file is open as a text file, I can then tap it and get an option to save it).
The files from the website work with iPhones and iPads. The files are school reading assignments and the students with iPhones just tap the link from the website and and they are shown an option to open the file in iBooks. The file then opens in iBooks and they can save it from there, if they want to keep a local copy. I'm assuming that since the files will work with iPhones, that there's no problem with the site or the files.
I'll try the two step process (open in the browser and save to the SD card) and see if that works (although if it does take two steps, the guys with iPhones will be laughing at me).
I should note that none of the students with Android phones are able to get this to work. The teacher provides PDF versions of the files so they can be read on a smartphone, but eBook versions would be easier to read. The schools IT department doesn't understand what's causing the problem.