MCU_SRAM_SIZE_KB is missing in the following instantiation
mci_reg_top #(
.AXI_USER_WIDTH(AXI_USER_WIDTH),
.SET_MCU_MBOX0_AXI_USER_INTEG(SET_MCU_MBOX0_AXI_USER_INTEG),
.MCU_MBOX0_VALID_AXI_USER(MCU_MBOX0_VALID_AXI_USER),
.MCU_MBOX0_SIZE_KB(MCU_MBOX0_SIZE_KB),
.SET_MCU_MBOX1_AXI_USER_INTEG(SET_MCU_MBOX1_AXI_USER_INTEG),
.MCU_MBOX1_VALID_AXI_USER(MCU_MBOX1_VALID_AXI_USER),
.MCU_MBOX1_SIZE_KB(MCU_MBOX1_SIZE_KB)
)i_mci_reg_top (
Opened an issue to the open source as well