Actually that tool takes a .qza/.qzv file, not a plugin.
To see a plugin’s citations you can use: qiime dada2 --citations
However, there are usually going to be more citations that just that because a plugin can use shared (and potentially citable) functionality, so I’d stick with qiime tools citations, just hand it an artifact/visualization.
Note:
You will have needed to have generated your data in version 2018.4 for there to be any citations present, otherwise you’ll just see “no citations” because we hadn’t taught QIIME 2 to do that until this last release.