To set Google drive as your default save location on a Chromebook, follow the steps below

• Open Chrome, navigate to the top right corner, and click the Three Dot Menu.  Then select "settings".

• Expand the "Advanced" menu on the left of the screen and click on "Downloads.

• NOTE:  THIS STEP IS OPTIONAL!  Toggle the "Ask where to save each file before downloading" to on.  It will become blue.

• Next, click the "Change" button to begin the process of selecting your download location.

• On the next screen, click on "My Drive" (1), click on "New Folder" (2), name the folder "Downloads" (3), select it and click "Open" (4).  

• Close all your windows and test it by downloading something and checking to make sure it's in that folder.  YOU ARE DONE!