Your model raises a few issues which merit consideration.
The first and primary issue which you need to consider is the location (client vs. server) of the file whose content you wish to read. When developing, both client and server are the same machine, and therefore are easily confused, but consider that in a deployed web application they will (practically) always be different machines.
Now, client (= browser) side files always require (due to browser-imposed restrictions) user intervention, comprised of selecting and uploading the specific file the user wants, and this is indeed performed via a File Input Field. The good thing about files selected via File Input Field, is that there's no need to "read" the file, as once selected, it is already available in File Input Field/<Value>/Content. However you cannot access it directly on the client side, and the File structure which serves as the <Value> element must be passed in tact to a server side process, plus, if this is a text file whose content you wish to display in a text field, as in your demo, you'll need to convert it from binary to text. This is demonstrated in the following screen shot:
Server-side files are handled differently. There's no File Input Field equivalent, as these files (and their paths) are assumed to be preset by the modeler, which indeed is the case for the Help.txt file included in your model, which can be loaded as follows:
Note that the path specified for Read File and Read Binary File is relative to the models folder of the project.
I hope this is helpful, but if it raises more questions, please post them.
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