For all details check (https://github.com/IBM/powerai/issues/268 4).
Make sure you have the right conda channel prepended:
conda config --prepend channels https://public.dhe.ibm.com/ibmdl/export/pub/software/server/ibm-ai/conda/#/

then install the powerai wmlce that you want e.g. 1.7.0 (most recent as of this writing):
conda create -n my_new_env python=3.7 powerai=1.7.0
conda activate my_new_env