In order to set up a dining option that will force a user to enter their table number you need to first mark "Ask for table code" in the setup section under Configure > Menu > Setup > Serving options:
Now, in the location settings, scroll down to "Dine in table code ranges" and enter the range which you want to enable a customer to select a table.
If you have more than one range you can enter them with commas, for example if you have 101-118 on the main floor, and 201-207 on the second floor, you can enter in that field:
When a customer will select to dine in at that restaurant, they will have to enter the table number they are sitted at:
The table number will be printed on the receipt: