You can be eligible for gifts from the advent calendar only if you have made at least one deposit before. So, you need to make a deposit prior to receiving the gifts. You can claim your welcome bonus or skip it. But it’s almost certain that you will need to complete the wagering for the welcome bonus before claiming the next offer.
https://casinobest.ca/faq/can-i-claim-a-welcome-bonus-and-a-gift-from-the-advent-calendar/