download issue using window 10 and latest version of firefox

I am using windows 10. this computer is about 6 months old. i am using the latest version of mozilla firefox. I was on facebook playing one of their games. out of nowhere, the game just stops. i refreshed the game and got a message telling me that i needed adobe flashplayer to use this game. when i followed the help instructions telling me how to check if my computer has flashplayer, i am told i DO NOT have adobe flashplayer. ok, so i try to download it to my computer. i do not know how to take a screen shot to show you the message. it goes through the install process. asks me if i will allow this program to make changes, yes. the program does the install and up pops a message telling me "insufficient user privilege to install application". what does this mean and where did my flashplayer disappear to? i was just using it and it disappears in the middle of a game? help please