@DLago
I haven’t tested this directly within Acumatica yet. However, for one of my customers, We created a custom field to store a hyperlink to a document that needs to be shared. The document itself is stored outside of Acumatica, in a secure folder where only a specific group of users has access.
When a user clicks the hyperlink from that field, it redirects them to the document hosted on platforms such as SharePoint or AWS, depending on where the file is stored.
You can follow a similar approach create a custom field (or use the Notes/Files section) and paste the external document link there. This can help you provide controlled access to specific files for your subcontractors.