You must have the latest NVIDIA drivers installed on your host operating system (Windows or Linux). Conda cannot install the low-level hardware drivers for you.
Once there was a developer named Leo, who spent his days building deep learning models. One morning, he was tasked with training a new neural network, but his environment was a mess. He had conflicting versions of Python and his GPU wasn't being recognized. Leo knew that to get his NVIDIA GPU talking to his code, he needed the conda nvidia cuda toolkit