Logging in to the IOS app should work much like the web app. You'll provide the sub-domain where your account is located and give the same username and password that you would normally use on the web app.
If you find that you're unable to log in please double check your login details, sometimes it's just a typo. If the problem persists or you see a Network Error message please try "hard closing" the app and re-opening it.
Performing a hard close and re-launch of the app:
1- With the GroovePacker app open on your device double press the home button.
2- When the screen changes to show the apps you have recently opened as tiles, swipe up on the GroovePacker tile to remove it from the list.
3- Tap the home button again and then tab the GroovePacker app to open it.
This process should clear any outdated cache info that could be preventing your login.
If problems persist please contact support so that we can assist.