All installation instructions are in more detail here.
First, clone the repository and enter the directory:
git clone https://github.com/picrust/picrust2.git
cd
Next, install the required dependencies listed here.
Install PICRUSt2 into it's own environment using conda:
conda env create -f picrust2-env.yaml
source activate picrust2
pip install --no-deps --editable .
Finally, run the tests to verify the install was successful:
pytest