Trying to copy amazon .azw files into my iPad from mac

I've got several Amazon kindle files (.azw or .azw3) files on my Mac that show up inmy Mac's Kindle reader but I can't seem to copy them to my iPad. I tried putting them into Dropbox but they can't be opened on the iPad end. Tried to email them to myself but the attachment won't open in kindle. I've tried to simply drag n drop from the Finder window to my iTunes iPad display but that doesn't work. Tried in iTunes File > Add to Library (cmd-O) and that didn't work. I've done an Internet search of this topic but the responses are from <2009 and no applicable to current operating systems or apps. Amazon's help pages don't provide any info either.

Can someone please provide links to possible solutions on the Internet or your own way of doing this? It's really frustrating trying to move content from a Mac to an iPad and I can't imagine why Apple has made this so difficult. Or at least that's my perception.

I have an iPad 2, 64GB wifi only, running iOS 8.3, My Mac is a late 2012 Mac mini running 10.11 (15A204h) as part of the Appleseed program (yes, I know it's beta and anything that can go wrong will go wrong, but still...), iTunes v. 12.1.2.27

Thanks for any tips or info leading to a resolution.

-Tod