If you're getting an error "Invalid login. Customer access is disabled." the issue is generally solved by enabling web services (all users that wish to use CloudExtend must have NetSuite web services enabled for their role).
Contact your NetSuite Admin and ask them to enable NetSuite web services for your role.
Your Admin will likely know how to do this already or they can follow the steps below.
Navigate to Setup > Users/Roles > Manage Roles.
Locate the role you want to modify. Click the corresponding Edit or Customize link.
Click the Setup subtab.
In the Permissions dropdown list, select Web Services or SOAP Web Services (for NetSuite 2020.1 or higher)
In the Level drop down list, select Full.