See explanation below. Explanation: You need to edit the Lead to Opportunity Sales Process business process flow by making the step mandatory. In the site map, select Sales Settings. Under Customization, select Business Process Flows. Select the Lead to Opportunity Sales Process business process flow. In the Develop stage of the business process flow, select the Customer Need step. Tick the Required checkbox to make this step mandatory. Click Save to save the changes. Reference: https://docs.microsoft.com/en-us/dynamics365/sales-professional/customize-business-process-flows