Hi @BTasdemir,
Section "3.2 Arm Platform Memory Map" from the RT1060 Reference Manual, address 3000_0000 to 3FFF_FFFF is reserved. The GUI Guider User Guide that you are referring to uses address 6060_0000, which is the FlexSPI memory region (for external flash). Are you using an RT1060 as well? If not, make sure you refer to your MCU's memory map to ensure that you are using the proper are for external memory.
BR,
Edwin.