I have a EVAL-HMC1023LP5 and driving it with a HMC6356 USB interface card. This interface card appears slightly different them the one shown in the the photos
The usb interface card is using DLP2232H. https://www.dlpdesign.com/dlp2232h-ds-v11.pdf.
There does not appear to be a SPI output coming from this output header. Do you have a schematic for the HMC6356?