Good afternoon Eman,
pick_closed_reference_otus.py: command not found
That's a script that's part of qiime 1, but don't worry, Qiime 2 can do closed-ref OTU picking too!
See this thread for more information about how to build a PiCRUSt compatible OTU table using Qiime 2. 
Let us know if you have any questions.
Colin