How to upgrade from v3.6.3 to v4.4.5?

Running into issue while upgrading to 4.0 on Ubuntu 18.04. I am following the guide. On install, I get error - arm64 is not supported.
But the guide mentions to add source repo with arch=arm64. What am I missing? How do I fix it?

There is already an issue on this forum mentioning the exact issue I am facing but without an answer