what are all the things I need to create my external loader

I do know that the following code passes which includes enabling memory mapped mode (see bold).  I also have been using these same quadspi drivers in my application that uses TouchGFX in memory mapped mode as well, so I do know memory mapped mode must be working with TouchGFX, right??  You actually created an external loader for me for this part that I've been using for quite a while but needed to develop my own to support other alternate Flash parts in the future.

uint8_t buffer_test[MEMORY_SECTOR_SIZE];
uint32_t var = 0;

CSP_QUADSPI_Init();

for (var = 0; var < MEMORY_SECTOR_SIZE; var++) {
  buffer_test[var] = (var & 0xff);
}

for (var = 0; var < SECTORS_COUNT; var++) {

    if (CSP_QSPI_EraseSector(var * MEMORY_SECTOR_SIZE,
       (var + 1) * MEMORY_SECTOR_SIZE - 1) != HAL_OK) {

        while (1)
        ; //breakpoint - error detected
    }

    if (CSP_QSPI_WriteMemory(buffer_test, var * MEMORY_SECTOR_SIZE, sizeof(buffer_test)) != HAL_OK) {

        while (1)
        ; //breakpoint - error detected
    }

}

if (CSP_QSPI_EnableMemoryMappedMode() != HAL_OK) {

    while (1)
    ; //breakpoint - error detected
}

for (var = 0; var < SECTORS_COUNT; var++) {
    if (memcmp(buffer_test,
       (uint8_t*) (0x90000000 + var * MEMORY_SECTOR_SIZE),
       MEMORY_SECTOR_SIZE) != HAL_OK) {
        while (1)
       ; //breakpoint - error detected - otherwise QSPI works properly
    }
}