Account Linking - Organisation does not exist

I have been following the documentation found here -> Meta Developers it works amazingly for accounts in the organisation, but gives me the following error for those who aren't:

Unsupported post request. Object with ID '660449250483406' does not exist, cannot be loaded due to missing permissions, or does not support this operation

I've seen another organisation have linking for members who aren't apart of the organisation, I reached out but they said they couldn't tell me how they did it. Any help is welcomed, I really want to get this to work!
Thanks,
Clash.