When a team has a no rate defined in the Rate Matrix, the 'populate from assignments' on the cost plans still calculates a forecast cost for the team. The article describes how this cost is calculated.
Release : 15.7
Component : CA PPM SAAS PROJECT MANAGEMENT
To calculate the team rate the cost plan was picking up a row from rate matrix that has all '*' in the columns, this is sort of a 'catch-all' row.
If that was not the case and if there was no rate association in the rate matrix, then when you were populating the cost plan ( 'populate from task assignments' ) we would land with an error "REVMGR-20728: Rates and Costs are both missing for one or more roles/resources".
“Since a team is a resource, you can select it for the Resource column in a cost and rate matrix. Set up the financial properties on the team resource profile and go into the matrix that has the Resource column configured and you can select the team resource.”