I changed the maxAllowedContentLength to
<requestLimits maxAllowedContentLength="5024000000" />
The 'maxAllowedContentLength' attribute is invalid. Not a valid unsigned integer
According to MSDN maxAllowedContentLength has type uint, its maximum value is 4,294,967,295 bytes = 3,99 gb
So it should work fine.
See also Request Limits article. Does IIS return one of these errors when the appropriate section is not configured at all?
See also: Maximum request length exceeded