To highlight a text you need to:
1-Activate the select tool, by clicking on the select tool button.
2-Start selecting the text on the page. (with the touch event)
3-As sson as the touch event finishes (touch up event), a popup will appear where you can choose the desired action.
4-Click the Ok button to confirm the action.
Note, The license needs to be activated, and the file needs to opened in write mode.
Check the attached screenshot.