Use the Effective Access tool to analyze permissions.
Here I have shared out the Data folder and check the access to a sub-subfolder.
Select the user you are having a problem with and check the "Access limited by".
net share data
icacls E:\Data\Subfolder\Sub-SubFolder
Note that "Access limited by" indicates Share and the permission on the share says "everyone read".
The "(I)" on the folder permissions indicates that the acl is inherited from the parent folder.
Verify that the permissions that you think you set are actually in place. Check the permissions on all folders/subfolders starting with the root folder that you shared.