how do you get the old generation version on ps5 when you have the old gen disc

my cousin has FC24 on disc for his ps5 and he wants to play pr clubs with us, i have an xbox one (old generation) so he cannot play with us using his new generation disc. all my friends who have FC24 on ps5 have it digitally so they were able to download the old generation version for free however my cousin who has the disc version is unable to do that. can anyone help ?