Configuring Custom Fields as Template Association Fields
To configure a custom field as a template association field:
1. Navigate to Setup > Object Manager.
2. Launch the Template Match Value object.
3. Click Fields & Relationships.
4. Click New to add a custom field.
5. Add the new field as per your requirement. For example, add Account as a Lookup field and Category as a Picklist field.
6. Save the changes.