the flashloader download is the first part of the image download process.
Can you verify that the wires from the FTDI cable are securely connected to the BW16? It looks like the flashloader download may have been interrupted, thus it could not proceed with the rest of the download.
It looks like the MAX3232 chip does not support a high enough baud rate. The upload speed on Windows & Linux default to 1.5 Mbps, while it seems the MAX3232 chips only go up to 250 kbps.
There should be no need to use the MAX3232 chip, have you tried connecting the FTDI output directly to BW16?
Uploading firmware uses a higher speed to reduce wait time.
I would suggest try connecting the FTDI directly to BW16, or use a 3.3V USB-UART converter if you are concerned about the voltage levels.
This is not explicitly stated, but in the user manual chapter 8 on using the ImageTool, it can be seen that the upload speed can be configured. The Arduino IDE upload process work in the same way, but uses the default speed of 1.5 Mbaud, which can be seen when using a logic analyzer to capture the upload process.
You can choose to download the Image Tool, then use it to upload the images compiled in Arduino IDE.
The Arduino IDE compiled images can be found in \AppData\Local\Arduino15\packages\realtek\tools\ameba_d_tools\1.0.7
Thank you.
After converting the ArduinoIDE Source File (.ino) to .bin, I set the baud rate to 115200 using AmebaImageTool and downloaded it, and it was successful.