When you created that sticky element, place links inside it and give them a class.
Now go through your sections on that page you want the links to scroll to when clicked and change style when that section is visible.
For each section go to the settings tab and assign them a id! Make them unique 
Now go back to the links and also in the settings tab in the link settings click on “link to sections” and choose the id you want it to be assigned to!
If you now have one of the section in the middle of the viewport, click on the corresponding link in the sidebar and you should see an additional class on that link called “current”
When this class is active you can set the styling you want all the links to have when their section is active. Give the basic link class that is not active (no “current” class) the transition=all attribute and they will have a smooth transition, no abrupt switching!
Hope this helps!