You'll need to use HTTP nodes in your workflow that can POST and GET a specified URL.
First, POST a file to the Manual Integration route. You'll need you API key and Model ID.
Authenticate using an Authorization header containing only your API key.
The Model ID must be sent as a form parameter.
In this POST response, there will be a polling_url attribute, save its value.
Wait 3 seconds.
Loop GET requests on the polling_url until the response contains a result_url .
Note: make sure to configure the node to not follow redirections.
Alternatively, loop on the polling_url until it redirects to the result.
Important: in all cases, wait at least 1 second between each poll.
A GET request to the result_url will contain the result payload.