Freelancer students can work on missions on crème de la crème to the extent that they have the corresponding freelance legal status in their country of fiscal residency. crème de la crème provides its users with guides and guidelines to help them with their registration.
As a company, you are perfectly allowed to work with a student vested with the freelancer status (e.g. Auto-entrepreneur in France, Sole Trader in the UK). You do not need to follow any administrative procedure and there won't be any additional fee regarding the mission besides the price you and the freelance agreed upon.
Some freelancers also trade under a moral entity and some of them will have their own LLC.
crème de la crème is working with certified accountants and lawyers to guarantee the rigorous legal application of the procedure on the platform.