You can follow this approach to add plugins to docker containers.
So, I just ran the sequence you provided:
... against the full-length SILVA 138.1 reference database, as processed via RESCRIPt, with feature-classifier classify-sklearn and I was able to obtain the following assignment:
d__Eukaryota;p__Parabasalia;c__Tritrichomonadea;o__Tritrichomonadea;f__Tritrichomonadea;g__Dientamoeba;s__Dientamoeba_fragilis
I also obtained the same result using ACT. Is this what you were hoping to see?
-Mike