Hello MJ W,
Do you have access to a ftp server or web server where you can load the files? if you choose a service like google drive, users will still need to authenticate. Either way, as long as the server uses SSL encryption (https), then the file should be accessible on Tableau Online.
Using this method - Opening a File from Google Drive with a URL action or Web Page Object | Tableau Software with Tableau Online will result in a prompt on google drive.
What issues are you encountering trying to set this up? and what services have you tried to utilize?