I can’t redeem my railcard code on the app
You can only claim your Railcard by entering the discount code on the Trainline website. It won't work if you try and enter the code in the Trainline app.
Trainline will ask you to enter the code under 'Total to Pay' before checkout.
Please don't checkout until you've applied your discount code otherwise they'll charge you for the Railcard.
Once you've checked out you'll get a confirmation email.