NOTE: If you don't want site members to see the report, consider creating a folder with different permissions where only site owners can access the report.
Steps to Run the Sharing report.
Open the site where you want to run the report.
On the Settings menu, click OneDrive settings.
Create a New > Folder (here we created MyShareReport Folder), select the Folder and click Save, and then click Run sharing report again.
The report may take some time to run depending on the size of the site.
CSV format
For items shared with direct access, the report contains one row for each user / item combination. SharePoint groups are shown in the report, but not individual users inside them.
For items shared with a link, the report contains a row for each signed-in user who has used the link or has been sent the link through the sharing dialog box. Links emailed directly that haven't been clicked, and Anyone links are not included in the report.
Resource Path - The relative URL of the item
Item Type - The type of item (web, folder, file, etc.)
Permission - The permission level the user has on this item
User Name - Friendly name of the user or group that has access to this item. If this is a sharing link, the user name is SharingLink
User E-mail - The email address of the user who has access to this item. This is blank for SharePoint groups.
User or Group Type - The type of user or group: Member (internal), Guest (external), SharePoint group, Security group or Office 365 group. (Note that Member refers to a member in the directory, not a member of the site.)
Link ID - The GUID of the sharing link if user name is Sharing Link
Link Type - The type of link (Anonymous, Company, Specific People) if user name is Sharing Link
AccessViaLinkID - The Link ID used to access the item if a user's permission to an item is via a link.
