This is because the recipient has never transferred TRX to his address, so the address is not activated. Please do not worry, as inactive wallet addresses can be used to receive tokens normally.

Note: Transferring to inactive addresses will cost you an additional 1.1 TRX, so please reserve at least 1.1 TRX in your TRX wallet when transferring the full amount, otherwise the transfer will fail.

Learn more: How to activate your TRX wallet