Flash won't install on Firefox (Mac w Sierra)

I'm on a Mac version 10.12.3 (Sierra) using Firefox.  When I go to download Flash Player (Adobe Flash Player Install for all versions ) Step 2 inevitably stops in the middle and reloads to a page reading:

Unable to connect

Firefox can’t establish a connection to the server at fpdownload.adobe.com.

    The site could be temporarily unavailable or too busy. Try again in a few moments.

    If you are unable to load any pages, check your computer’s network connection.

    If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.

What can I do?  Seems like this should be simple yet I've spent hours on the forums and it seems many, many people are having similar problems that aren't getting solved.