We do not allow booking fewer than three tickets. Can we configure this rule?

Open the resource configuration. Add a Reaction.

Enter a name. Select the reaction type — Show error. Enter the error message text and click Add condition.

Select Shares and set the maximum value to 2. This will prevent users from booking one or two tickets. Save your changes.

The error message will be displayed with a red line. It appears both when selecting options and on the cart screen.

The Place order button in the cart will be disabled.

See it in action: