KJV:

9 And from under these chambers was the entry on the east side, as one goeth into them from the utter court.

NASB:

9 Below these chambers was the entrance on the east side, as one enters them from the outer court.

The service entrance is located below, that is, well below the level of the inner court. The service entrance is located on the east side of the building, in the place where the gallery located in the outer court is adjacent to the row of the gallery located in the inner court. This entrance is used by the Kohanim and Levites working on the outside of the inner court.