Locate the file or folder you would like to share externally, right click, select Share and then Share again.
Under General access on the ensuing screen, pull down, select Anyone with the link, select Copy link, and enter the email address of the person with which you’re sharing in the “Add people” field, paste the link in the “Message” field, and then hit send. Confirm with Share anyway.
The recipient will then need to confirm their email address when opening the file.