Add a new Matomo widget from your dashboard.
Select from the list of preset metrics, or build your widget from scratch.
Select the Domain where your Matomo account is located.
This should match the domain you use to log in to Matomo.
Add your Account name or hosted URL.
Enter your Matomo API key.
This can be generated by going to Personal > Security.
Click Connected.
Once authenticated, you'll be taken to the widget configuration screen, where you can customize your widgets.