I don't know how it is called, but I mean where you can also enter page numbers. I want to enter some quotations, but they appear on every page. How can I enter a different text on every page?

What you are talking about is the footer. (This is the bottom half of a header/footer pair.)

If what you want in the footer also appears in the body of the document on that page, the simplest way to incorporate it in a header or footer is the StyleRef Field.

Each Word Section has three headers and three footers which are independent of one another and which may or may not be displayed depending on which options you have chosen. Sections / Headers and Footers in Microsoft Word 2007-2013

If you can, use the StyleRef field instead of changing the footer.
Header/Footer Settings Recap

Otherwise, instead of putting your quotations actually in the footer, you could use text boxes that are positioned in the footer area. These would actually be anchored to a paragraph on the page. This is more trouble than the StyleRef field but much less trouble than actually having a different footer on every page.

Depending on the number of pages and the amount of energy available, how about saving each quotation as a custom property and using a field in the footer?

One property per page?? Plus the field coding to apply a different one to each page?? Good Luck.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

Quite right … looking at it again, I realise my mental model (so early in the model) was incorrect; I was imagining/inventing a single field that would step through values in a list. "Dreamer, nothing but a dreamer …" :-}