Create a vertical line. Create your text. With the text selected, choose
Text/Fit Text to path and use the tip of the arrow to point to your
line. Space the letters out a bit if you want.
Open the Character Formatting docker. With all your letters selected
with the TEXT tool, type 90degrees into the Character Shift/ Angle field
of the docker. Adjust spacing as needed.
Now select the just the line in the Object manager (Ctrl+click) and give
it no outline and no fill so it doesn't show up in the final product.