UPDATE: Apple approved our expedited review, and version 2.1.4 is now available in the app store. Thank you for your patience while we worked through the issue.
The most recent iOS Client that was released (v2.1.3) has a bug that causes issues with new installations which stops users from logging in or creating new accounts from their iOS devices. We have uploaded a new build and have requested an expedited review with Apple. We sincerely apologize for the inconvenience. The web client is unaffected, as are any users who had already created an account on their device. Hopefully the fixed client will be available quickly.