The CYUSB3ACC-006 HSMC Interconnect board for FX3 is for a HSMC port.
The HSMC connector used in the schematics of the design is QTH-090-04-L-D-A (coming under Messanine Connector type) which can be checked from here: QTH-090-04-L-D-A Samtec Inc. | Connectors, Interconnects | DigiKey
The schematics for the HSMC Interconnect Board can be found from the link: https://www.cypress.com/file/133876/download
In the schematics, i found that the PCLK on the FX3 side is connected to Pin 35 (PCLK) on J6 connector and PCLK on FPGA side is connected to Pin 175 on J1C connector.
This is done inorder for the interconnect board to be used between FX3 and Altera FPGA's to implement the AN65974 appnote which uses the slaveFIFO interface to implement a master-slave data transfers.
The appnote also provides respective FPGA source files for both the Altera and Xilinix FPGA boards in which the PCLK is routed to Pin 175 of the HSMC connector on the FPGA and the Interconnect board is designed to complement the slaveFIFO interface as well.
The link for the app note: https://www.cypress.com/documentation/application-notes/an65974-designing-ez-usb-fx3-slave-fifo-interface
Hope this information helps.
Thank you for your Answer. Have a nice day.