Well, I don't know what to tell you, maybe try a different browser? Maybe copy/paste that URL?
If you google "BDP-83-60-1011_2.0" the earliest date shown on the web is May 30, 2018, much later than the November 26, 2014 date for the BDP83-60-1110 firmware listed on Oppo's BDP-83 support page.
Why Oppo does not list the firmware for the HDCP2.2/HDMI2.0 compatibility issue on that support page is beyond me, but they did the same thing for the BDP-93/95 HDCP2.2/HDMI2.0 compatibility firmware as well.