Hi Alex,
Greetings, the code you are looking for has been EoL for a couple of years now https://support.juniper.net/support/eol/software/junos/#2 and that is the reason why you would not be able to download it from the official website, all of these codes (EoL) are archived hence you would have to open a case with JTAC in order to get it.
If this solves your problem, please mark this post as "Accepted Solution" so we can help others too \:)/
Regards,
Lil Dexx
JNCIE-ENT#863, 3X JNCIP-[SP-ENT-DC], 4X JNCIA [cloud-DevOps-Junos-Design], Champions Ingenius, SSYB