What is Google Apps Sync?
Google Apps Sync for Microsoft Outlook is a plug-in developed by Google that lets you use Outlook to manage your Google Apps. Put simply, this means you can manage your UM-Gmail, Calendar, Contacts, notes, and tasks using Microsoft Outlook. The Sync tool will run unobtrusively in the background and take care of all the "behind-the-scenes" technical stuff that has to happen to make that possible.
After you have downloaded, saved, and initiated the installation of the file, you will be prompted to enter your credentials. Please do so, as shown below.
On the next screen, simply press Create Profile. (At this point, it is normal for your computer to hang or even give a "Not Responding" status for a few seconds. If it does, give it a moment to catch up.)
Once it finishes, you'll be shown the message below. Simply press Start Microsoft Outlook to open Outlook. At this point, installation of the Sync tool is complete. In the future, you just need to open Outlook... no need to run the Sync tool again.
After clicking Start Microsoft Office, Outlook will open and ask you which account you'd like to open. Chose the one ending in "Google Apps." (If you click the Options>> button, you do have the choice of making this the default.)
When Outlook opens, you will see your messages and content begin to populate. Outlook is building a local cache of your mailbox, and you will see the following screen as it does so. You can safely use Outlook at this time, simply click Close on the status window to hide it.
A notice about the local cache
If you're already familiar with Outlook, you may have heard of the phrase "cached mode." This refers to Outlook building a local copy of your mailbox. Because configuring Outlook using this method does not provide a real-time interface with Gmail, the only mail you'll be able to interact with from within Outlook is mail that has been "cached." The Sync tool will allow you to specify how much of your mailbox you want to store in the "cache," with the most recent content cached first. You can change this setting by right-clicking the Sync icon in your system tray, as seen below. Any mail that does not get synced because it's beyond the local size capacity has to be viewed using the Gmail web interface.
Select Unlimited (Slowest) option if you have many emails on your G Suite account