I have tried requesting personal data from one company. They quickly said they didn't have anything associated with me; I believe it's just identified by an id

I have tried requesting personal data from one company. They quickly said they didn't have anything associated with me; I believe it's just identified by an id that I don't know and that isn't linked directly to myself. I wouldn't be surprised if they did not link email addresses (and other user-accessible identifiers such as a phone number) anymore just to avoid having to give you your data if you request it.