Hey d0evils_agent,
If you've logged into Apex (or another EA game) on PlayStation, it's already linked to an EA account. If you're wanting to use that same EA account to play on PC, you'd just need to make sure you're logging into the EA app with that same EA account information. If you're playing through Steam, you'll be prompted to link your Steam to an EA account as well, so it just comes back to knowing the EA account information.
If you don't have access to the EA account or aren't sure where your PSN account is linked, you'll want to contact support. If you create a new case here and select Game Support > EA Account > I want to update my EA Account information or I need help logging in to my EA Account, you should be able to get in touch with support so they can take a look.