Question 1: "Does he have obligation to collect sales tax from his Maryland"
Yes, for Taxable Sales.
Question 2: "and other state customers?"
If the sale qualifies, for that other State, and perhaps, an additional local/regional rate, combined. Not for all States. Not all States have sales tax requirements.
With the ruling in South Dakota v Wayfair, it is more reasonable to get a service to handle the sales tax nexus requirements. Otherwise, you have to become informed in every State and Local Tax agency requirement.
"Level Up" is a gaming function, not a real life function.