At this point it's clear that Adobe's refusal to continuing delivering its latest Acrobat Reader software for Linux is just down to spite.
Unfortunately there are still examples of PDF files out there created with Adobe's proprietary tools, particularlly fill-in-the-bank forms, that you can only work with using Adobe's Reader.
Reader 9 can still be made to run on Ubunut 18.04 LTS, if you can get a copy of the last .deb generated for it in 2013.
AdbeRdr9.5.5-1_i386linux_enu.deb
Here's the ftp site where you'll find this file, as well as the rpm, bar.bz2 and bin packages (the last two should work on generic Linux -- but it's up to you to follow the dependency train to get it up and running):
ftp://ftp.adobe.com/pub/adobe/reader/unix/9.x/9.5.5/enu/AdbeRdr9.5.5-1_i386linux_enu.deb
Install using apt to load most of the dependencies:
$ sudo apt install ./AdbeRdr9.5.5-1_i386linux_enu.deb
Then install the rest of the dependencies:
$ sudo apt install libxml2:i386 libstdc++6:i386
Hey, it's really old (ancient) software!