Is there a possibility that the user is referring to an eBook version of the answer key? If so, the installation steps might involve syncing with an e-reader app or platform. But I think it's safer to assume it's a standard PDF file based on the phrase "answer key PDF."
Next, if they already have the PDF file, they might need instructions on how to open or install it on different devices. For example, on computers they can use PDF readers like Adobe Acrobat or free alternatives. On mobile devices, apps like Adobe Acrobat Reader or Google Drive. For tablets or e-readers, maybe using PDF apps or cloud services.
I should avoid technical jargon as much as possible, making it user-friendly. Maybe include examples of PDF readers and cloud services that are commonly used.
Also, some answer keys might be part of an instructor's resources. So the user might need to contact their teacher if they're a student. That's an important point to include.
But wait, could there be other methods? Like using a document viewer app on a tablet or syncing across devices. Maybe include steps for different operating systems—Windows, macOS, iOS, Android.