What does Article VI say about administering religious tests to candidates of public offices?

Article VI, Paragraph 3

"The Senators and Representatives before mentioned, and the members of the several state legislatures, and all executive and judicial officers, both of the United States and of the several states, shall be bound by oath or affirmation, to support this Constitution; but no religious test shall ever be required as a qualification to any office or public trust under the United States."

"No religious test shall ever be required" means they are not permitted. This is designed to prevent discrimination against, or exclusion of, people for their religious beliefs (or lack thereof), in holding government office, and is consistent with the Establishment Clause of the First Amendment.
there should be no tests administered