Many newer apps aren't compatible with older TVs (or with other devices, such as Humax boxes). It's not unknown for people to buy TV sets that have only just come onto the market, only to find that certain apps cease to be supported just two or three years later. So I've got a nasty feeling that Moggie and/or ILA might be trying to do the impossible:
https://www.cordbusters.co.uk/itvx-streaming-app-wont-work-older-devices/
However Sony Bravia TV sets aren't listed in that link as models that are known to have problems, so it
might be possible for him to get it to work. The very first thing that Moggie needs to do is to check his spam folder, to see if the missing email is hiding in there.
For anyone who definitely can't get ITVX directly onto their smart TV, a workaround is to use something like an Amazon Fire TV Stick or a Roku device.