Hi Danny,
I made two edits: a remark after the Rscript instructions that there's also an Ubuntu package (although I didn't indicate a preference), and a second bullet point to add that if /usr/lib/systemd/system doesn't exist, then try /lib/systemd/system instead, and also to check the install path for R, and edit your file if necessary.
I installed using Rscript, but I'd be willing to test out what happens if we use the Ubuntu package instead. Do you know if it's difficult to uninstall via Rscript? I have no familiarity with using it.