Navigate to google.com/takeout and log in, if necessary.
Select only the data necessary for archiving. In most cases, you can click "Select None," then switch on the button next to Drive. Click "Next."
Select the file type, archive size, and delivery method (the defaults are most likely fine.) Then, click "Create Archive." The archiving process will begin. If you selected the default of "Send download link via email," you can close the progress window and await the email with your download link(s).