Yeah, this is pretty important. Microsoft Dynamics GP 2016 – Document Attach for Project Expenses (PTE)
Microsoft Dynamics GP 2016 – Document Attach for Project Expenses (PTE) – Microsoft Dynamics GP Community
Microsoft & the GP EcosystemGP 2016
Archived post from 2016. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.