You need "Marvell AT Interface" drivers. These are often included in "LTE MiFi Generic Driver" packs found on community forums like Hovatek .
Often provides the tool along with specific firmware for Airtel M2 devices at their resource thread. Mifi Tool 1.4.0.0 Download
Enter the required IMEI or MAC info and click the corresponding buttons to write the data to the device. Download Links You need "Marvell AT Interface" drivers
Connect your MiFi to your Windows PC via a USB cable. Mifi Tool 1.4.0.0 Download