I received an email from MakeUseOf offering to read and download a guide about using iOS 7. When I tried to download and save the file I got a message saying the file was not downloadable. What gives?
I think that you are trying to download using a download manager which had shown this message.
Normally,you can download by going to top right hand side,choose your format in mind and then right click on the format and click on save file as or save link as.
There is a download button on the right of the guide, click on PDF and it should download, at least it did on my machine.