I don't think you'll be able to use Ubuntu 16 to install RetroPie, even if you check out the 4.5.1 version - most of the packages will not work with that old Ubuntu version.
You can try installing the current Debian release or a more recent (18.04) Ubuntu version and install RetroPie as explained in the docs.

@barbudreadmon Looking at the Udoo website, this is a much more powerful device than mine with better processor, graphics and more RAM. I think this explains why I can't emulate PSOne on such an old low-end machine.