Your Apple ID is required for a number of things.
Your Mac or computer , your iOS device ( iPhone , iPad )
That is then used on your apps and software
- iTunes ( computer and device )
- Music ( on your iOS device )
Check your device and make sure you are signed into these apps.
Along with your Apple ID you need to know your password
Don’t know your password or if you need to change it , here is where you can manage your it.
This all works well with the latest operating system on your mac , Mavericks.
Where you may run into issues , such as syncing is when you have an older operating system on your mac , such as Lion , Leopard , Snow Leopard.
Check if you can make the move to Mavericks