UEA / LCR gig car parking

Theres some old posts about this but I'd like some clarification. Ticketmaster says it's free if parking for a gig in the main car park if you take and return a "green token" - I presume this is outdated info as there's numberplate readers now.

Last night there were a lot of equally confused people when leaving. Going to the pay machines charges you a flat £1 after 6pm causing long queues in the freezing cold to reveal you CAN pay on the Ringo app too, but my question is; is it supposed to be free when just parking for gigs does anyone know?