A file has been added to the Event Notes & Attachments related list. The end user is added as an Event Team Member but the user is not the owner and cannot access the file.
Veeva Events Management automatically shares events and their related objects with team members with permission.
Objects that are shared automatically include:
Expense_Header_vod (Expense_Line_vod uses a master-detail relationship to Expense_Header_vod, and is automatically shared when the Expense Header is shared)
Salesforce File is not shared with permission automatically.
The administrator could grant permission to the user. Currently, Salesforce requires MODIFY ALL DATA permission if the user wants to access or delete the file.
CRM Help Documentation: Event Team Members