You might want to read the DICOR website FAQ's. Specifically the one about mold/mildew on TPO and EPDM roofing membrane. They say there's nothing in the chemical composition of the roofing membrane that will (or can) support mold/mildew. The only way mold will grow is if there is some organic material deposited on the roof (tree sap, bird dung, etc) that can be used by the mold as a food source. The website goes on to explain how to clean and maintain your roofing material. It's a good read and has all the answers you'll need to resolve your problem.
https://dicorproducts.com/faq/#mold-mildew
This link will take you to the DICOR Roof Care Handbook, another source of good information:
https://dicorproducts.com/images/RudysRoofbook_16.pdf