User Profile

We are a small development team that will develop an app for a 3rd party SME. The SME has already an Apple Developer Account (as organization with DUNS id) enrollment. The idea is that we will be invited as members of its development team. After reading the help section of the App Store Connect (https://help.apple.com/app-store-connect/) I still have a couple of questions: Is it required that we (the invited development team) must also have an Apple Developer Account? The developer account holder does not possess any Mac devices. Can we use our Mac devices (with our invited Apple Ids) to develop, debug and deploy the app? If I understand correctly, we need to get "Admin" rights (https://help.apple.com/app-store-connect/#/deve5f9a89d7), correct? Thank you, Dimitris