How long does it take before I can withdraw the earned Crypto cashback?

This depends on the policy of the store you shopped at! When you go to the specific shopping trip in the Rewards page, and you click on it. You should see a countdown timer that shows how long you still need to wait before you can withdraw your earned Crypto Cashback.

Be aware that some of the memberships give you a reward time reduction. Gold. For example, offers a 50% reward time reduction!