A cricket ID is your personal account on a sports exchange platform. Once you have one, you can view live odds on cricket matches, place back-and-lay bets as the game is happening, and withdraw winnings to your bank account or UPI. It's not a separate login for every match — one ID covers an entire season, and usually every other sport the exchange carries, not just cricket.
People specifically search for "cricket ID" because cricket, not football or tennis, is what drives most of the demand for these platforms in India — IPL season especially sees sign-up traffic spike hard.