To connect you cloud environment through a CAP to a DoD network, you must have VDSS and VDMS services in place. Project Hosts is the only CSP with a DISA IL5 PA that offers these services for your application.

What are VDSS and VDMS?

The DoD Secure Cloud Computing Architecture specifies that for a cloud application to connect through a CAP to the DoD network, the cloud environment must be protected by a Virtual Datacenter Security Stack (VDSS) and a Virtual Datacenter Managed Services (VDMS)
See Diagram

Do It Yourself VDSS and VDMS

VDSS and VDMS are not included with Azure DoD, AWS, or any other IaaS offering with a DISA IL5 PA. If you deploy on one of these, you have to build it yourself.
See Azure DoD DIY Guidance
Project Hosts DoD IL5 Clouds

Or Have it Done For You

The Project Hosts PJHFPC is the only cloud offering with a DISA IL5 PA that includes built-in VDSS and VDMS for your applications and workloads.
See VDMS Control Responses