“Above it were the cherubim of glory overshadowing the mercy seat. Of these things we cannot now speak in detail.”
If you went back to Exodus and read all the verses describing the Tabernacle and the items in it and how they were used and how often you fully understand why the author is not going to repeat that information here. It is enough to allude to it since his reading audience is as aware of the information as he is. The language here suggests that the details are not necessary for the point he is making in his argument here. The author is more interested in how this whole thing functioned. How it worked then might very well help us to understand how it works now. It also may help us to see why a different plan of action was required.
The writer is not really interested in the Old Covenant provisions except as they help us understand the provisions of the New Covenant. All the Old Covenant preparations and activities provided a yellow brick road to Jesus and the New Covenant. In that sense, the material he is covering is a road map to his main point. He wants to lead us from the shadow to the light.
Task for Today: You need to know about the Tabernacle to understand the priesthood and the entire system of reconciliation to God. But, the thing you need to grasp is not the Tabernacle and its items but the plan of God to create in you the temple of God using Jesus as your high priest. Jesus is the connection from your inner man to the inner sanctuary of God.