As soon as you finish installing Google Drive for your Mac/PC or mobile app, the device can sync with Google Drive on the web. Devices with Google Drive only sync with My Drive, the section of Google Drive on the web that contains files and folders you've uploaded and Google documents, spreadsheets, and presentations that you own.
When everything has synced between your device and My Drive – give it a few minutes if you have a lot of stuff – you can access and launch the same files from all your devices.
See sync in action
Syncing is built-in – you don't have to do anything to set it up other than connect to the Internet.
If you're curious to see sync in action and find out if your My Drive files and folders are syncing properly on all devices, try this small test: make a change in My Drive on the web and then check to see if that change appears on the other devices where you've installed Google Drive. You should see your change everywhere that you have Google Drive.