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Next, navigate to the new Folder, and click on Folder Tools. Select Folder Sharing Settings, then click Create Local Sharing Settings. Click on the Make Private button and confirm that fields for All registered Synapse users and Anyone on the web have been removed. Save your changes.
The folder with can then be shared only with the specific teams that the entire project is shared with, and not the general public. Removing local sharing settings on an item will assign default permissions from the parent folder or project.
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