How do I turn on Touch ID?????????

I got this app in lite and I saw Touch ID and I wanted to use it but the box to turn it on is grey and when I press it it wont turn on. So I thought I had to get the full version to make it work and I did but it does the same thing. If anyone knows how to make it work please respond!!!!
Other than that its a cool app.

BlueCupcake09 about My Wonderful Goals * To-do note for my daily life