To switch between pages, you can use the navigation bar.

Access the navigation bar at the bottom of the interface to switch between pages seamlessly.

Shows the current spread in this case page 56 & 57.

Moves you to the First Page

Moves you to the Previous Page

Moves you to the Next Page

Moves you to the Last Page

Alternatively, you can use the Ladder button at the top right of the designer to navigate to any particular spread you're looking for

(shown in the red box in the image above)