Can't get my free trial to start.

hi guys! i'm new here so im not sure where this is supposed to go, but i figured this was the best place. i wanted to try out the better campus free trial, and i went through with setting my payment method up, but it hasn't updated and i'm worried i wont be able to use/cancel it before it charges my card. when i tried to just start the free trail again, the button doesn't take me anywhere. would be grateful for some help. thank you!