Windows 7 has not been supported by Microsoft for a (long) while. I assume that you are using a modern browser that supports state-of-the-art encryption, while Windows 7 does not. As R won't bring along its own encryption libraries, R is stuck with an outdated interface from Windows 7.
Unfortunaltely, there is no way we could provide an insecure interface without bringing all the other users at risk. Therefore, you will have to use the R import with two files.