Video explanation here:
Q: Do I need to claim my rewards?
A: No. You will realize your SOL staking rewards when you unstake mSOL for SOL, but the value of your mSOL is continually growing. If you choose instant unstake, you will receive your SOL plus SOL staking rewards. If you choose delayed unstake, you must return to the Marinade DApp to claim your SOL. You can sign up for Dialect alerts by clicking on the bell icon next to your wallet in the Marinade DApp to be notified when your stake is ready to be claimed via email, telegram, SMS, or wallet.