In the Target app, click on the little icon with your name in the lower right hand corner, then hit Profile, and there should be an option in there to type in your team member number to add your discount to your account. It’ll add your discount to your wallet and automatically apply it whenever you scan the barcode in Target Wallet
I think you have to add two zeros before the TM number. Also you can sign into your Target account on your computer and put your team member number in as a promo code and it permanently adds it to your account and carries over to your phone.