Monitor a folder for PDFs with the keyword "Invoice" and download them to another location every hour with FileBrowserGO's Custom Tasks.
First give your task a name like "Invoice Update"
Locate the folder with your invoice PDFs on your work server.
Filter the documents to any containing the word "Invoice".
Now filter the list of documents to any that are PDFs by using ".pdf".
Copy the matching files to your iPad in a folder called Invoices.
Tap manual and change it to 1hr. This will run this Custom Task every hour.
See our help section on Custom Tasks.