Create Donut chart in Tableau.
First create Calculated Field and type 0 and drag sum(0) into row shelf and then create pie chart.
and again drag sum(0) into rows and second sum(0) and click on it and choose duel axis and then choose sum(0)2 & increase the size and then go to color and choose white color.
and choose sum(0) and drag region into label and drag region into colors
and then sales into labels
go to sum(0)2 and then drag sales into label and click on label and go to 3dots and type "total sales" and right click on blank space and go to 3lines and go to "zero line" and click none. and then right click on edit axis and uncheck "show header".