I think to get it so the text can’t be highlighted it may just have a clear symbol over it (alpha 0%) but that would just be a guess.
If you notice as the text scrolls and as it appears at the bottom you can tell there is some sort of mask over where it comes up from to get that fade in look.
Are you putting the textbox with scroller on its own layer? That is how I did mine and just put empty frames in front of it so it started where I wanted to on the timeline. Might not be the neatest way but it works for me.
