In case you have Zoho single Admin log in integration then please do the needful. 

Step 1. 

Log in to your Zoho account and click on the Icon shown in the below mail.

Step 2.

Then go to Modules & Fields as shown in the below image.

Step 3.

Step 4.

Step 5.

Create two custom fileds named as AssignedAgentIdentifier & AssignedAgentName.

Exactly in the same way. These should be single line fields. 

Once done please call at 8860089620 that this is done.