Instagram connects through Instagram Business Login, which requires your Instagram account to be a Business or Creator account (you can switch account type in Instagram's own settings, it's free).
Artec reads your profile info, media, and insights so brands can see your real performance. Access is read-only: Artec can never post for you.
During connection, Instagram lets you untick individual permissions. If you decline some, your account will show as Limited in Artec: see the article on the Limited badge for how to fix it.