Set the values in .env to your liking. Important is to change at least YOUR_SECRET_KEY to something random.
The preset superuser is admin with password admin. Login in with this useraccount, create a new superuser and delete admin. The database containing userinformation is instance/database.db inside the folder where this file.
To enable notification via Discord, create a discord-bot and apply the generated token to .env. Set the credentials of the channel you want to notify in .env, and add the bot to the channel. Please refer to the discord developers website for detailed instructions!
Start server with docker-compose up and browse to the url you specified. The startup can take a while, as elastic needs to be fully available before the webinterface is started.