How to solve the problem as follows

As shown in Figure 1, it is a schematic diagram of the MCU architecture. There is no Flash inside the MCU, only a small Bootloader ROM. Its function is to move the program stored in the external SPI NOR Flash to the SRAM in addition to the boot process. The control right is handed over to the program execution of SRAM.

Figure 1 the schematic diagram of the MCU

I wrote User Code with Keil MDK v5.25. I want to burn User Code to External SPI NOR Flash through Keil MDK Flash Download function and CMSIS-DAP (SWD) under the above-mentioned MCU architecture. When execute burn with Keil MDK, I encounter a situation that cannot be burned, the problem and the related screen are as follows:

1. Unable to burn, display warning window and problem as shown below

2. Scatter-Loading Description File as below,

3. The Flash Download settings are as follows (FLM File must be burnable):