You don't need a membership card to earn rewards.
To earn rewards online, just use your perks email address at checkout.
To earn in-store, let the team member know that you have a Cotton On & Co. Perks account. They will then be able to link your sale to your account via your email address or mobile number if this has been added to your account.
The team in store can also issue a new card for you if you would like one.