Create a Heroku account.
https://elements.heroku.com/addons
Make sure you're logged into Transposit, then click this link to open the Heroku settings dialog, enter a name, and click Save.
In the Integrations list, where your key is now included, click Authenticate.
The browser opens, letting you log in to your Heroku account.
Heroku is now enabled to interact with Transposit.
Now that you've configured your integration, add one or more of the integration's actions to an automation, test the automation, and then add the automation to an incident type.