We have an authenticated WFS from Drone Deploy that has an API key. ArcGIS Online and ArcGIS Pro both have the ability to include the api_key in the request.
Is it possible to include the custom request in the WFS Reader?
Question
WFS Reader and custom requests authentication
+47- Celebrity
So you should be able set up a custom Web Connection in FME to dronedeploy which should be able to be used in a WFS reader.
You can read more about it here: FME Options: Web Connections (safe.com)
There are also a couple of differnt tutorials floating around on the community here somewhere which go through a few specific steps for example services