OTA curl command problems

Hi when I type in the command
curl -v -F file=@C:/Users/nadekumar/Documents/ota_mdash/GpioReadWrite_MDash.ino.esp32.bin http://mdash.net/api/v2/devices/device6/ota?access_token=4t0r99WN91rD7ArhDcEkwe3g

I get message":"Unauthorized can any one help me in this regard

Is your access_token an API key, or is it a device token? It should be an API key.
https://mdash.net/docs/userguide/ota.md#ota-updates-using-curl