If you can't login for the first time besides that a tenant admin set you up as a MindSphere user with an appropriate MindSphere user role, it is possible that you haven't set up your Webkey account yet.
Solution
You can create your Webkey account by clicking on the 'create an account' link on the login page where you normally enter the credentials to access your MindSphere tenant.
Enter your personal details on following screen and click on 'Create'.
Before you click on 'Continue' on the next screen, please check your inbox and click on the 'Verify Email' button in the email with subject 'Verify your email' you have received.
Once done, click on 'Continue' in the browser tab where you started the process.
This will then log you in to your tenant.
Notes