I’m trying to get into the next adventure chapter 30 but it’s saying I have to decorate so I went..

To have flowers count on newly purchased items, construction must be complete and red ribbon be removed.

When it says you need to "decorate", the game wants you to add more Flower value to your island to advance to the next level/scene. How many more you need is shown in the upper right, next to the flower icon.

Flowers can be added to your island in several ways: moving items from storage to island, buying decoration, upgrading buildings, renovating landmarks, and sending Jack's plane on a flower delivery. When you buy decoration, the construction must be complete and the red ribbon removed, before its Flower value will count. Buying decoration of higher Flower value will get you further in the game.