The Holy Spirit is not a “repository” of God. The HS is God. At least, we trinitarians believe that. I’m assuming you are a trinitarian.
God, however, has seen fit to speak through His servants, the prophets, and the NT contains instances of prophets still being prompted to deliver specific messages to God’s people, none of which rises to the level of Holy Scripture.
Yes, Scripture has authority, in the sense that where there is disagreement between Scripture and a claimed "statement of God," Scripture is taken as correct.
But it is not a complete repository of all that God has said and done (cf. John 21:25).