I think it is saying "Windows always on top" because, as you state, it is opening on this browser and this post ("Always on top"), As you can see from Wolfies snip
Assuming Edge is your Browser, What you need to do, is decide what site you wish to have as your opening page. Make a copy of the address.
Now click into the settings, as previously indicated.
Open the item on the left "On Start up"
Choose "Open a specific page"
Paste in, or type, the address you have already selected, Now, whenever you open the browser, that should be it.