Sign in error to App Store Connect

I can not log in to the App Store Connect. Error message: 'To access App Store Connect, you must be an individual or team member in the Apple Developer Program, or invited by an individual to access their content in App Store Connect.' (https://appstoreconnect.apple.com/login?errorKey=ITC.signin.error.invalidUser.asc)

As far as I know, I am an individual (and only) member of my account.

I want to edit the App Store Connect's 'Users and Access' section.

Thank you for your help!

Kata