You will need the following:
- An active MPN ID in the country location where you are onboarding to in Partner Center.
- Global admin credentials for a Microsoft account.
- A registered legal business name, address, and phone number for the country location you are onboarding.
- An admin for the Partner Center account, if not the person who will submit the Partner Center enrollment for onboarding as an indirect reseller.
If you are not a Microsoft Partner yet and do not have an MPN ID, you can following the instructions here to join the Microsoft Partner Network.