You may need to change the start of the microflow.
The Community Commons module has methods (such as StoreURLToFileDocument) that would allow you download content from a URL and store it as a file. Once you have the content downloaded as a file, you could continue with the example microflow.
Hope this helps.
The last comment in the thread below seems to suggest that accessing a server file isn’t possible in the cloud using StoreURLToFileDocument? Or am I reading incorrectly? Trying to find a solution to automating excel imports that I can do on my own through app design without involving other resources outside of Mendix (if that’s even possible)