HR material is material you must produce to to achieve the purpose, goals and objectives for your department.
Examples of HR material you should produce.
Volunteer personas
Job descriptions
Volunteer handbook
Signage
Mock-up of volunteer area
Volunteer management tool (software, excel sheets)
Work schedules
Volunteer goodie bags?
Detailed budgets
Plan for external communication (marketing for recruitment - in collaboration with marketing team)
Plan for internal communication
Etc.