Power BI Count criteria by Unique ID

Hello,

I need help finding an expression for a table.

I have two tables, one of the unique customer IDs, one of product information including products assigned to a customer id and its manufacturer.

I need to find a way to count how many times a specific manufacturer appears in the product list by customer id.

The current formula i have that incorrectly results in a count of how many times the manu. appears:

Sum of Manu Prod= Countrows(FILTER('Prod list',[Manufacturer]="MANU01"))

I understand this is incorrect but I cannot find an additonal expression to count those appearances by the unique code/customer ID code.

Thank you,

bhelp