Where can documents be stored when using the Project Accelerator? I've seen images of a 'Document' tab in the accelerator next to Business Case, Risks, Issues, Status, but it's not clear where the project work (docx, xlsx, pptx, pdf, etc) are actually stored and accessible for the Enterprise.
It's probably a customised version, you can customise the solution to add in any other features you need. There are few options when it comes to documents in Dataverse model driven app including SharePoint Online integration, Timeline control, File column type on the table - really depends on your requirements. Research the options and see what works for you.