Hi @Laura_R,
If you download the files on that page, you can then use QIIME 2 View, to look at the provenance information. The provenance says 138' not 138.1 or 138.2. I recommend you follow the tutorial that @Julio linked above and construct your own classifier. You can pick the steps you'd like to use during construction.
For example, here is one quick way to make an amplicon specific classifier. Though, I'd likely add the qiime rescript cull-seqs ... after the amplicon extraction step.
If you are unable to build the classifier on your machine, checkout this post.
-Mike