Hi, if your problem is (was?) just how to install the code you linked, do this:
Copy the code into a text program (TextEdit will do), save it as "TeamViewer.json" (put it) into this folder: ~/.config/karabiner/assets/complex_modifications **
… and import it via K-E's tab "Complex Modifications", [+ Add rule], scroll down to it, check [+ Ebable].
It should work at once.
(** the "~" symbol stands for your user folder, usually: /Users/userName )