The game keeps asking me to visit the storage before letting me start the next chapter. I have bought..

As you know, in this game you need a certain number of flowers to progress to the next level. These flowers can be obtained from decorations, which can be bought from the store (cash register icon) or moved out of storage (large container ship) where you may have placed them earlier.

If the game is asking you to visit storage it means you have already purchased items with enough flower value to take you to the next level, except that you have put them away into storage.

Simply visit the storage ship and place the needed amount of decorations from out of it onto your Island. If you do not have enough land space to do this, you can temporarily move smaller items into storage and instead place larger ones with greater flower value (until you earn enough compasses to open up more land).