What does this mean?
This means that the code you've entered is expired or invalid.
Double check you entered the email correctly. Better yet, enter the email again.
(if using Gmail) Check Updates or Promotions categories. Google will sometimes filter emails into there.
If you've downloaded Playbook on multiple devices (iPhone, iPad or Android), you will need to go through each login separately.
This means:
Please contact us at support@playbookapp.io.