edit your /etc/hosts to add 127.0.0.1 matrix.local
Run this script to generate a signing key
chmod +x init.sh
./init.sh
docker-compose up -d
and wait a bit...
docker exec -it synapse_synapse_1 register_new_matrix_user -c /mx-conf/homeserver.yaml
You can go to your instance at http://localhost:8008