Charles Ellicott Commentary Exodus 40:5

"And thou shalt set the golden altar for incense before the ark of the testimony, and put the screen of the door to the tabernacle." — Exodus 40:5 (ASV)

You shall set the altar of gold ... before the ark. —Not inside the veil, but outside, in the Holy Place; nearer, however, to the veil than either the table or the candlestick. (See Note 1 on Exodus 30:6.)

The hanging of the door —i.e., the curtain at the entrance to the Tabernacle (Exodus 26:36; Exodus 36:37, and other similar verses).