Adding segments to end users analytics account to connect data to Tableau

I am trying to add a few dimensions and measures through Google Analytics; however, when I add them, they do not show up on the field area.

According to this page: I need to "ensure the segments used in the existing workbook have been added to the end users analytics account". I have tried looking up information on how to add segments to the end users analytics account on Google Analytics, but I've had no luck. Does anyone have any idea how or what it means to add segments for the end users?

I also posted this question on Tableau Community, if you'd rather answer it there, here is the link: