Lightroom 6 is NOT Lightroom Classic. It was the last perpetual licensed version, And is no longer supported by Adobe. Adobe has taken down all of the updates for it. If you check your account online the 6.14 download might be available there. If not, then you'll have to contact Adobe directly to see if they will provide a link to the 6.14 update. That will be the final update you will ever be able to get for that version of Lightroom. It is an end-of-life version. Here is the link where you can contact Adobe:
Please post your System Information as Lightroom reports it. In LR click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.
Just another Adobe customer; My Sys; APP: LRC 9.4, PS 21.2.1; CMP: WIN WS 16GB OS 10 v1909 (18363), mid 2015 MBPr 15” 16GB MACOS 10.15.6; 4K EXT DSPY; CAM: Canon 5D Mk III, Fuji X-T3