While it should be possible using Safari it's not. I attempted it last week and everything went fine until the last step, when an AC popup appears and it asks you to check a box and agree to the terms and conditions.

I defy you to scroll across the window, check the box, and hit enter. Lets just say that i'm a tad stubborn and made "many" unsucessful attempts to complete the transaction.

I'm not sure if the issue is with the AC website or with mobile version of Safari, but I hope it gets resolved.