A "restricted" message when linking your Instagram and Facebook Page is almost always an error on Meta's side, not an issue with Scaled Creator.
What usually clears it
The restriction often lifts on its own after a couple of days, so waiting and trying again is worth doing first.
In the meantime, enable two-factor authentication on the account and change the password to something strong. Then try linking again in an incognito or private browser window.
If it persists, open a support ticket with Meta if that option is available to you. Meta's support chat is usually only offered to verified accounts.
This one sits entirely on Meta's end, so there is nothing to change inside Scaled Creator to fix it.