you could start by being more specific ^^ what is a timeline/progressbar for a book? you mean a “your are here” kind of thing? how did you create the flipbook? it’s hard to give you answers without more input..
the book , that i’ve created is actually an induction booklet for company staff. now, i want them to know as they progress with the book, how much induction process they have completed. the link that i’ve posted above is the same book that i’ve created. i haven’t added anything yet in those pages.