I was using the video I mentioned and do my own spin. In the Family, you define number of alphabet including space to determine your signage text.

Then, remove the repeater

For each alphabet, you define the value. If it is space, you simply delete it to create a space.

The family has a built in arc height and width to get the text arc which you can adjust. Sadly if you want width to be 2m and arc to be 1m, it will break. So you have to set width as 2m while arc to be 1001mm or 999mm to overcome the constraint.
Check out my Revit youtube channel - https://www.youtube.com/user/scourdx