Welcome to the forums, MM, and sorry for the trouble! There are few different things that could be going on here. However, barring unusual circumstances, you shouldn't be asked for credentials unless you have sync enabled. Since you're not using the iPad app yet, you can probably just turn sync off for the time being if that's what's causing this.
If that doesn't resolve the issue, it's probably going to be easiest to sort out if you send some screenshots of your Sync preferences in the Mac app to our
support ninjas or give them a call at 800.315.6664 so they can help you over the phone.