Hi,
Thank you for the help,
It worked for me but before flashing actual .bin file, we need to convert to the format it accepts.
The Image editor will do all the necessary things to the .bin file generated by IAR/MCU Expresso IDEs.
Download the Connectivity QTool found in the same page as the Image Editor and install it. The installation folder for this tool will contain the libgcc_s_dw2-1.dll, so run the QN908x_Image_Editor_v1.0.0.exe from that location. This will set the format and generate a .bin file.
This converted .bin file can be used to flash to the MCU in ISP mode.