Hi mar0512,
Well, the file size is definitely within the 100 MB file-size limit, but it sounds to me that the file may be overly complex (large number of pages, lots of different fonts and graphics), and the ExportPDF service is timing out before it can process the entire file.
You mention that you want it in Word format so you can make notes. Have you tried using the commenting tools in Reader to add notes to your document? That may be the easier route for you.
(If it turns out you don't really need the ExportPDF subscription, I can help cancel it for you and process a full refund, since you just signed up.)
Best,
Sara