READER DOES NOT WORK

I have an HP laptop with windows operating system.

I am just trying to read my first book on the Adobe ePub, which I have never used before . This is to read a book from archive.org. The first problem is that I cannot page down. The slider on the right does work, but I have to switch on and off the window on the left with bookmarks on it. The  page on the screen is grey not white.   I contacted adobe help but they said they no longer support digital editions, whatever that means.

By the way I am 75 years old. HELP!