The text of this email is slightly wrong if autoenroll is selected. I'll code up a fix tonight (see https://edx-wiki.atlassian.net/browse/LMS-2551).

The text you have above ("You have been invited to be a beta tester for <course name> at <URL>. Visit <link> to join the course and begin the beta test.") is what the text will be if Auto-Enroll is *not* selected. On Edge, <link> will be the course's about page; on edx.org, <link> will simply be the site name (www.edx.org).

If Auto-Enroll is selected, the text will be:
"You have been invited to be a beta tester for <course name> at <URL>. Once you log into <site name>,  you will see <course name> listed on your dashboard."