Still need to add credit card details. Can understand why you might want to do that, but it is now a barrier too high for me in order to just try out something which could be interesting.

EDIT: As per the comment below, this does indeed work. I initially tried on my phone and I kept seeing an error to complete the missing fields. On my desktop, it worked. Thanks.

You can get the free credit if you just press ENTER after entering the promo code (without needing to enter the credit card details). It's not very intuitive, but it worked for me.

I've fixed this by adding a button for replying :)