Hi @Mashuk 
I think you are running into an issue that was addressed in the 2020.2 release of QIIME 2. Unfortunately, it seems that the picrust2 plugin may not be compatible with newer versions of QIIME 2 (see this comment). There is some discussion with hints about possible work arounds here, and here which might be helpful. I'm not sure if this is an issue that needs to be addressed in the framework or in the picrust2 plugin. Sorry I can't be of more help right at this moment. 