As of April 3rd, 2018, the Champions Program will no longer be issuing material prizes from the reward catalog. You can read about their full announcement on why they are making this change here.
If you have redeemed your T-shirt prior to April 3rd, 2018, within 2 hours after your redemption on the MuleSoft Champions portal, you'll receive a link from Champbot to place your order. Please allow up to 10 weeks to receive your T-shirt afterwards, depending on the country you live in.
Contact the Champions team directly at firstname.lastname@example.org if you have yet to receive your T-shirt after 10 weeks.