Right click and select "Open With" and choose to open the HTML file with Google Chrome (or another browser of your choice). It seems like your computer is opening the HTML file in Notepad and showing you the raw code instead of loading it on a webpage.
Viewing post in Community Service [v2.9.2] [Future!Phantom] comments
Since I don't play the game on mobile I'm not entirely sure of the process, but from what others have said you need to access the game through your devices file explorer. It works similar to a file explorer on PC, and has a few more options available. I believe a few previous comment threads on here have more detail about how they were able to get it to work.