As said, the 'Plans and Pricing' do not include 2017
see: Plans and pricing | Adobe Acrobat DC
Yes, Adobe is doing it's best to hide this option... Here are some instructions I compiled on how to get to it, anyway.
Go to the Adobe Products Page: https://www.adobe.com/products/catalog/software.html and search for "Acrobat".
Click on the Buy button next to Acrobat Pro 2017, and then change the "I want to buy" option to "Full License" (or "License Upgrade" if you have a qualifying earlier version).
Then select the other options and click on Add To Cart, and proceed to checkout. You'll get a full license, not a time-based subscription.