When activating an order with a contract attached, the Revenue Cloud sates rep notices that...

The Asset Contract Relationship toggle is not active in the Setup -> Revenue Settings -> Automatically create Asset Contract Relationship.

The sales rep did not manually create the Asset Contract Relationship object in order for the Contract to be linked to the Assets.

The Contract does not have the Revenue Lifecycle Management record attached to it, so the system does not automatically create the Asset Contract Relationship records.