When first joining DRC, all new member start on the Green Tier. On the Green Tier, members receive Surprise & Delight Cashback (such as the $10 Welcome Reward and a Birthday Reward). However, in order to start earning and accruing Cashback on transactions, they first need to reach the Gold Tier by transacting 3+ times totaling to over $600 within a rolling 12 month window. Once on the Gold Tier, members will be able to earn.
To move up to the top Sapphire Tier, within a rolling 12 months members must dine 5+ times totaling $600.
To prevent being downgraded back to the Gold or Green Tier, members must maintain these same spend and visit thresholds with a rolling 12 months.
You can read more about the DRC Tier levels here.