When guest users access a SharePoint page containing BindTuning web parts (or other third-party web parts), they may encounter an "Access Denied" error message or see an unrendered web part instead of the expected content.
This issue typically arises because guest users, by default, lack the necessary read permissions to the Tenant App Catalog, specifically to the web part's resources located within the ClientSideAssets directory. This is a common occurrence as guest accounts inherently have restricted access for security purposes.
Enable Web Part content for Guest Users
To ensure custom web parts function correctly and display content for guest users, you need to perform the following two actions:
1. Grant Read Permissions to App Catalogs
Guest users require explicit read permissions to both the Tenant App Catalog and any specific site collection App Catalogs where the web parts are deployed. This allows them to access the necessary web part resources.
Action: Ensure your guest users have been granted read permissions to the relevant Tenant App Catalog and any Site Collection App Catalogs containing the web parts.
Read MVP Are Flyen's related article.
2. Enable External Sharing at the Tenant Level
Go to Microsoft 365 Admin Center:
Admin Center > SharePoint > Policies > Sharing
Make sure external sharing is set to at least "New and existing guests" or "Anyone".
3. Enable External Sharing for the Site collections
Go to Microsoft 365 Admin Center:
Admin Center > SharePoint > Active sites > [Select Site]
Make sure the External file sharing option on the Settings tab is set for at least "New and existing guests".
4. Confirm Guest Permissions on the Site
Add the guest users to the site
Give them at least "Read" permission
You can do this via:
Site Permissions > Invite people > Add members > Share with guest email
For further reading, refer to this comprehensive article by Laura Kokkarinen.