This is how I'd interpret it

Authority is both the object of the divine (thus placed in an intermediate/middle position between the divine and the common man and therefore subject to divine laws, for example those of mortality)
and an intermediary for the divine and thus an expression of divine authority and invested by God to keep order among mortals.

See here a wiki description of the divine right of kings for example:

The divine right of kings, divine right, or God's mandate is a political and religious doctrine of royal and political legitimacy. It stems from a specific metaphysical framework in which the king (or queen) is pre-selected as a heir prior to their birth. By pre-selecting the king's physical manifestation, the governed populace actively (rather than merely passively) hands the metaphysical selection of the king's soul – which will inhabit the body and thereby rule them – over to God. In this way, the "divine right" originates as a metaphysical act of humility or submission towards the Godhead. Consequentially, it asserts that a monarch (e.g. a king) is subject to no earthly authority, deriving the right to rule directly from a divine authority, like the monotheist will of God. The monarch is thus not subject to the will of his people,