I have admin role of an account and able to view the team in app store connect website but with the same account not able to view the same on developer.apple.com. Did't get what is going wrong here.
Update : Adding a user from developer.apple.com, redirect to the appstore connect. It means now there is no difference between developer.apple.com user and app store connect users.
App Store Connect team is different and Developer.apple.com access is different.
You have admin role on App Store Connect but not on developer.apple.com
Ask the owner of the account to give you access on developer.apple.com
Your client needs to add you in Apple Developer
App Store Connect only and only allows you to submit your apps to the App Store while Apple Developer allows you to create your certificates and provisioning profiles, sign your apps, and distribute development and ad-hoc builds.