1. Choose your core reward you like
2. Pledge additional money -> as much as the add-ons you like to have
3. When the campaign ends, your pledged money appears as spendable credit, which you can use to get the add-ons you want.
Due to the logistics and cost of postal (gets ever more expensive) products in bundles are shipped together once. If you want to get the Remarkable Inns book earlier for example (already available in retail) I suggest buying that from Loresmyth or Nord games, and back for Remarkable Shops only.
Don't see the answer to your question? Ask the project creator directly.