EddyLoop is a small app on purpose, and the docs match. Start with installing it, then read the rest as you need it.
Download the build for your platform, run it, and grant microphone access. The first launch fetches the speech model.
What happens on the first launch, where the model goes, and how to arm the microphone for the first time.
One timestamped text file per day, in a folder you choose. Nothing is stored in a database and nothing is encrypted.