Bubble has two primary mechanisms for sharing data between pages, both of which involve the URL.
Bubble’s primary way (which I don’t actively recommend) is to have a “Date type” associated with a given page. (By default, Bubble gives pages the type of “User”. But you can change this to any other Data type in your database. You do not need to set a page type. But, if you do have it, Bubble will force you to send a specific thing between those pages - otherwise you get the error you’re encountering).
The second method, which is much more dynamic, is to use URL parameters. This allows you to “add” things into the URL of the application through what’s called a parameter. (I have a handful of lessons on LearnTo that provide lots of great detail about URL parameters).
When you check the box “Send more parameters to the page”, it will open up a few new fields where you can name new parameters to be sent.
Just remember that when you start sending things between pages, you’ll also need to “retrieve” them by using the “Get data from page URL” function.
Dan (creator of LearnTo - 15+ hours of Bubble tutorials and live coaching)