Microsoft Sentinel SOAR to Fortinet FortiGate

Dear Microsoft Community,

Need your expert and assistance regarding this matter.

I tried to utilize the SOAR function in Sentinel to dynamically update address object to FortiGate which is detailed on https://github.com/Azure/Azure-Sentinel/tree/master/Solutions/Fortinet-FortiGate

I tried multiple times and follow step by step guide and stuck when i tried to run the playbook. The following are the screenshots which step the playbook failed

Expanding the steps, I found the following error:

Any hints or experience why I stumble on this error? I don't understand the Request Context too why 

Much appreciated for the help