Below is the response from CS team:
"We would like to inform you that you can redeem points from your Snap deal card in multiples of 4 (e.g., 4, 8, 12) to match the exact rupee value during manual redemption, where 4 Reward Points (RP) equal ₹1.
Please note, a minimum of 1000 points is required to initiate redemption."
Tried again with points in multiple of 4, it's successfully redeemed now 👍🏻