I thought we may be able to stick with Google Drive's cloud storage if I can figure out a way to manage PDFs and simulate a browser upload using Google Apps Scripts, but I'm not clever enough to figure out how to do this.
Needs to be cloud-based since everyone is working from home, unless you think a VPN to connect to a NAS or something would be helpful.
Postal mail orders are scanned in by us and sent to an email address, we use a web fax that goes straight to the email. Our customers can submit orders to us however they want - postal mail, email, fax, etc. Data entry looks like uploading a PDF to a new service ticket in the system and keying in the data from the PDF into the web page for that ticket. However, we are married to an Old Legacy Online Inventory Management system (OLOIM) that does not have such features. Ideally, an inventory system should have features to manage entering new orders.