The task is to count the number of customers who have made 1 order, 2 orders and so on.
Step 1: Create a new calculated field in Tableau called "Orders By Customer" and type
{FIXED [Customer Name] : COUNTD([Order ID])}
Step 2: Drag "Orders By Customer" to Columns and "Customer Name" to Rows
Step 3: Right click "Customer Name" and select Measure -> Count (Distinct)
Step 4: Right click "Orders By Customer" and select Dimension
Step 5: Right click "Orders By Customer" and select Discrete
Step 6: Right click "Orders By Customer" and select Sort
Step 7: Sort Order Descending and Sort By Field "Customer Name with Aggregration as Count (Distinct)
Step 8: Edit the tool tip by clearing the default and replacing with:
<CNTD(Customer Name)> customers have made <Orders By Customer> orders