Your question might be kind of broad in scope, but I think you’re looking for a very general answer. Basically, all the steps are in that post you linked to, but from a beginner point of view it’s probably a bit confusing.
In general, there are two different “worlds” being described. One is setting up a Google account using your PC and the other is logging into your Raspberry Pi, either directly by plugging in a monitor with the HDMI port, keboard/mouse via USB or through WiFi using the remote desktop software. Several of the Rasperry Pi steps are using a Terminal program and the command line.
The other difficulty I see in those instructions are related to which version of the Operating System (OS) your Raspberry Pi has. If you have Raspbian for Robots, there is an option to open up a Terminal for the command line (CLR) steps. But if you have the new DexterOS, that option for a Terminal is not immediately obvious.
I hope this helps in a general sense to get you headed in the right direction.