Usage of ‘at least’

Today I received an email from Skype, letting me know thus:

“Notice that Xbox now requires that you sign in at least every 5 years to keep your gamertag active”

This strikes me as odd, as a native speaker. To say to sign in ‘at least every five years’ would imply that it be a requirement to sign in every five years or greater, would it not? Does the above sentence somehow mean the opposite if what it means literally?

Thanks.

Edit: I just came to think that perhaps they had meant to say ‘at least once every five years’, but what they have written then seems like a mistake to me instead.

Context is very important in this case. You are required to sign in at least once every five years, so the least you can do to achieve that goal is to sign in once. Therefore "at least" is being used to describe that once in five year requirement. Don't get me wrong, it would have saved a lot of headache if they just added once, but it is technically correct.