Microsoft Surface Pro Registration

I am a bit confused on surface pro registration. The customer uses business M365 for email, etc. However, it seems that I must register the surface to a personal Microsoft account.  This has caused problems in the past - especially with OneDrive.  

Can also get confusing when every employee has a surface registered to a personal account even though the computers are owned by the business. Seems like a very decentralized and confusing approach. There must be a better way.

Can I use the customer business domain under their Business M365 account? It didn't seem to work but maybe I am missing something.

Would appreciate the best practice on how to properly (centrally) manage the registration for a dozen or so Surface Pro's.

Thank you!