There is no API key to create on your account: the platform cannot be queried. The connection works the other way round : we call your system on every delivered lead, through a signed webhook, or we write into your tool (Nova, OGGO Data, Google Sheets, Excel Online). Your developer needs an HTTPS endpoint able to receive a call, not a token to make one.
The only key you will enter is the one for YOUR tool, so that we can authenticate against it. It is not shown again after saving: never send it in a support ticket.