If you haven't already, download and install GoodSync.
With GoodSync, you can back up and sync to and from your Google Photos storage. To do so, follow these steps:
1) Open GoodSync and click the "New Job" button in the toolbar, or, in the "Job" menu, select "New."
2) In the New GoodSync Job prompt, enter the name of your new Job. Then, select "Backup" or "Synchronize" as your Job type.
Click the "OK" button when done.
3) Click the left or right sync folder controls to view the files and folders available for selection.
4) Scroll down, and select "Google Photos" from the list of supported services on either side.
5) A window will appear prompting you to authorize GoodSync to access your Google Photos account. Click on the "Connect to Google Photos" button.
6) A Google authentication page will open in your default browser. Enter the name of your Google account. Then click the blue "Next" button.
7) On the next step, enter the password of your Google account, and click the "Next" button.
8) Click the "Allow" button to grant GoodSync access to the Google Photos file system. You will then be taken to a page confirming that you granted access to GoodSync.
9) After permission is given to GoodSync, your Google Photos content will be shown within the GoodSync interface.
10) Select a folder that contains the data you wish to back up or sync on the left side.
On the right side, click "Google Photos" and select or create a folder you wish to back up or sync to.
Then, click the green "Apply" button.
11) Your Job is now ready to Analyze and Sync.
NOTE: To configure the job with automation or other settings, click here.