Sorry, but the days of replacing just the front digitizer glass on a modern cell phone are long over. The OLED display is bonded to the digitizer glass with something called OCA, or Optically Clear Adhesive. It takes an experienced hand with a vacuum fixture to successfully separate them, and requires vacuum and UV chambers to bond a new screen.
Given the amount and cost of the specialized equipment required, there's no economic sense in trying to replace the front glass versus just replacing the whole screen.
Be aware that unless you have an Apple authorized service center do the screen replacement, you're going to get a pop-up warning for about a week that you may have a non-genuine screen installed, whether or not you use a genuine Apple screen. You can also use the Apple self service program to do the job yourself, but you have to buy the screen from Apple, meaning it's not going to be cheap.
The only other way to get around the warning is to move an IC from the old screen to the replacement, but that's yet another operation that requires specialized skills and equipment.
Finally, you'll lose the True Tone function unless you have a piece of data copied from the old screen to the replacement with a device programmer, something like the Qian Li iCopy Plus programmer. This is easiest if you copy the data from the old screen, but it can be obtained from the phone; it just requires connecting to a Windows computer to do so. It can be done at any time, but does require removing the screen from the phone, so obviously the best time to do it is when you're actually doing the screen replacement. The programmers cost about $60, but you may be able to find a local repair shop that can do the copying for a minimal cost.
Oh, the part you linked to in your question is just the precut adhesive that holds the display onto the phone and seals against liquids.