Well, I think others have the question as well, here is a relevant answer.
Short story, the connections are wrongly pinned and will not allow the FPGA to boot from the bitstream in that flash. The shield was designed as a SLAVE board, mostly, with Stand-alone FPGA programming capability. the MCU (ESP32) is used to program as MASTER the FGPA(Spartan Edge Accelerator Board SPI Flash))