This mod will allow the admin to set a resource as a must view by guests/users before they are allowed to browse/view the rest of the resources.
After installing the mod, go to Options->XenForo Resource Manager. All the way to the bottom you will see 4 new options added which will allow you to make a resource as a must view for guests and/or users separately, enter the id of the resource that you want to set it as a must read and enter your own custom error message that you want to appear to guests/users when they get the read resource error screen message.
You can also exclude a group/s from this restriction at Groups Permissions->Forum Permissions->Can bypass force resource view restrictions: Set this to Yes and save the changes.
For more info, please have a look at the attached screenshots.