Hi @Zocuments, once the binary file has been created, what data is returned? For example, do you host the binary file at a specific URL and return the URL?
If so, then I think you would want to use a "text" input to allow for a string to be provided. Then the user building their Zap would need to connect the output from the document creation step so that the URL is provided to this Action step.
If you're not returning the URL to a hosted copy of the file, then you may need to use a deyhdration/hydration tool. There's a detailed example in the Platform docs under stashing files.
I've used something similar in a Zapier Code step to download a file from a Google Drive URL and feed it to the next step in a Zap, but since you're building an integration, it can be included directly in your code.