To view sync options tap Sync in the left hand nav bar
With this option you can sync attendance and meeting stats, along with group member and visitor numbers. So as check-in happens, new people are added or head counts are taken in UCare the numbers are reflected in the reports that you set up in Church metrics. You can even create Hillsong style health reports using this option.
Mailchimp is great if you need more advanced email options then are offered by UCare like visual email design or click tracking. This is a two way sync option so updates in Mailchimp or UCare will update the other app.
If you're already using Planning Center Services then you can use the sync option to ensure people's contact info stays up to date. This is a two way sync option so updates in Planning Center or UCare will update the other app.