d3rlpy is only tested on Linux and macOS. However, you can possibly run d3rlpy on Windows as long as PyTorch runs since it's the core dependency.
pip is a recommended way to install d3rlpy:
$ pip install d3rlpy
You can also install via GitHub repository:
$ git clone https://github.com/takuseno/d3rlpy $ cd d3rlpy $ pip install -e .