Samsung Galaxy S5 Mail download size problem
We had the same issue, and also tried setting it to "unlimited" without that solving the issue. We think the S5 is reading in bytes and S4 in KB. Finally, entering the limit in bytes solved it for us.

Can you try to put 1000000 in the limits and re-create your account on the S5, what choices of limits to you have while setting up your device at that moment?