While trying to import page in the T4 Page Builder component, it gives me permissions issue. Please note that I have the JA Pro membership and I have already logged into the website linking the membership. Same as this user https://www.joomlart.com/forums/d/44587-permissions-error-with-t4-page-builder-and-page-templates .
In Backend >> Components >> T4 Page Builder >> logout from your account there >> then logout admin account.
And clear browser's caches + login again, it should work.