Count values from different columns

Hi, im learning the basic and im stucked in a very simple dax. Maybe you can give me a hint on a table that im workingn on it.

I need count how many time a value from a column match a value from a different one. I need make another table coz i dont own the original table. I have done a matrix to show the visual and but now i have to work with a new table to summarize anothers value and make a target KPI

Here's the table. I need count how many time every client order a single Item

Im trying to make something like this.

Regards