Linking Facebook Page

Hi,

I'm new to administrating different pages on Facebook and this time I got this client that had this page for years and so the IG account, even tho Im set as Adm on the fb page I can't link both apps.

Here is the error I've been receiving:



I already try using the client facebook account with is the official Adm of the page but still I can't schedule and promote posts like that, it's been really a headache.

Thanks,