Adding strokes to text in illustrator is not as straightforward or intuitive as you might think. You cannot simply add strokes to the text and have it look the way you want. First of all the stroke can end up masking the text if it gets too thick. Second the text often ends up being distorted when exported. So how do we get around that?
After you have chosen your font and typed out the text
Turn the text into an outline: ctrl + shift + o
copy outline: ctrl + c
Paste to front: ctrl + f
Lock the front copy: ctrl + 2
select the text underneath.
Open up appearances window.
Add strokes and use rounded corners.