Thank you Bram. I have some updates.
FAISS installation 5 (1)

Not having faiss-cpu, just having faiss-gpu. Installed it by:
        conda install faiss-gpu cudatoolkit=10.2 -c pytorch


According to (1), it should be cudatoolkit=10.0, but that leads to downgrades that can lead to future problems.
down-grades762×311 21 KB
throws
AssertionError: You must install Faiss to use FaissIndex. To do so you can run pip install faiss-cpu or pip install faiss-gpu

Not having faiss-cpu, just having faiss-gpu. Installed it by

pip install faiss-gpu
Problem solved.
Cheers