If you read through this tutorial, you'll see that this focuses on downloading from the RefSeq target loci data. Specifically, if you read under the "Bacteria and Archaea: 16S ribosomal RNA project" section, you'll see that this data only contains sequences from "...bacteria and archaea type materials."
Unlike the other larger references databases (i.e. SILVA, GTDB, RDP,...) that contain a mix of environmental sequence data, type material, etc...