Hi thanks for the question
As per the linked document; I do not believe it is possible to get authorization to perform prohibited Penetration-Test activities (as detailed in the rules of engagement) as by definition the actions listed would be in violation of policy terms & conditions and (as also noted in the doc) may also have legal consequence
For further clarification you could raise a request through your Account representative or support.
For DDoS simulation/testing please refer to https://learn.microsoft.com/en-us/azure/ddos-protection/test-through-simulations
Hope this comment helps