It is possible to access deeper technical support from Intel than is normally publicly available by registering as a Non Disclosure Agreement (NDA) customer with Intel. This enables customers to access advanced support through an interface called Zendesk. The process for registering for an NDA is not very clearly defined though, with advice such as "Contact your local Intel representative" or "open a support ticket". I believe that what they are referring to is using the Intel Support website to connect with a support representative in your region of the world.
The Vision Processor D4 can be integrated in two ways. You can either integrate the D4 chip and its supporting components onto the motherboard of the hardware providing the computer processing, or you can use a PCB 'bridge' board called the 'Vision Processor D4 Board'.
Here is an example of the Vision Processor D4 Board on the site of FRAMOS, an Intel Approved Distributor.
System integration details for the D4 can be found in Intel's data sheet document for the 400 Series cameras, from page 71 onward.
In regard to your USB problems with the Up Board, could you provide more details, please? You can do this as a private message to me if you prefer not to disclose details of your product on this public forum discussion. If you are connecting the camera to the Up Board via the OTG micro-port rather than the full-size USB 3.0 port on the Up Squared, issues with USB related to power delivery have previously occurred with the basic Up Board model when used with the RealSense 400 Series. A mains-powered USB hub should provide sufficient power to the OTG port, though I appreciate that this may not be ideal for your product.
If you are using the OTG port for the camera, an alternate method to try would be to use Up's official OTG cable.
It looks as though part of the registration process for the Intel Resource and Design Center involves the need to be granted a CNDA (Corporate Non Disclosure Agreement). When you make your registration application, if you do not have a CNDA at the time of registration then its says that an Intel account manager contacts you directly to set the NDA setup process in motion.
I get the sense that support for members of the Resource and Design Center is separate from the public community support provided by the Intel Support department. Whilst I cannot find evidence that the R&DC make use of Zendesk, whatever private contact channels they have in place should still be effective.