What exactly is your subscription plan's upload and download speed? You said 90Mbps for download, but what's the speed for upload? Your test result is only 9.83 Mbps for download and 5.63Mbps for upload, that's weird.
Did you check your cable?
According to Netgear R6700 manual, The LED color indicates the speed: white for Gigabit Ethernet connections and amber for 100 Mbps or 10 Mbps Ethernet connections.
And in router's Advanced / Show Statistics webpage, it should tell you what connection speed is foor your PC.
it uploaded files at 48 megabytes per second to another computer on the network
it downloaded files at 2.8 megabytes per second from another computer on the network
How do you measure it? If you are copying files (we call it transferring, not uploading or downloading, since your files didn't go through WAN port) between machines on your LAN, it has nothing to do with your internet speed.