Use pip or conda to install the library:

pip install layoutparser

# Install Detectron2 for using DL Layout Detection Model
pip install 'git+https://github.com/facebookresearch/detectron2.git@v0.1.3#egg=detectron2'

# Install the ocr components when necessary
pip install layoutparser[ocr]

This by default will install the CPU version of the Detectron2, and it should be able to run on most of the computers. But if you have a GPU, you can consider the GPU version of the Detectron2, referring to the official instructions.