To send content items to your Dropbox account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account.
Then click on the save PDF button and choose the corresponding option, Send to Dropbox for articles

For book chapters, search for the option at the left side of the screen and click the corresponding Save to Dropbox button to proceed.