Hi there!
If you share a folder with another user, any changes made by that user to the folder will also be made for you. if the user adds af ileto the folder, it will be added for you too and this works as well for deletions.
Instead, you should send a shared link to the folder to the person you would like to share the files with.
A shared link creates a copy of files to send to someone, even if they don't have a Dropbox account. Think of these files like an email attachment – if the user downloads these files and you make further changes to them, these changes will not appear for the recipient. Similarly, if the recipient makes changes to the file, the original file in your Dropbox account will not be altered.
A shared folder creates a collaborative folder where designated editors can view, edit and delete any file in the folder. A shared folder member can also be designated as a viewer, in which case that member will not have the ability to edit or delete files in the folder.
To sync changes with the other user’s Dropbox you need to create a shared folder instead of a shared link. Please review here to see how each is created:
I hope this helps!