If you ask for permission, and receive it, then you are completely legal. If you use their servers and do not ask for permission first, then you are not legal, and they could take legal action against you. I don't know or have any connection with the company, so I have no idea of what kind of a chance you would be taking by not having permission.
If it is just asking for permission and not requiring any sort of payment, then why not apply for their permission?