If you work on linux and cannot edit some of the project files right after the first installation, you can run docker-compose run --rm php chown -R $(id -u):$(id -g) . to set yourself as owner of the project files that were created by the docker container.
If you have a TLS trust issues, you can copy the self-signed certificate from Caddy and add it to the trusted certificates :
# Mac
$ docker cp $(docker-compose ps -q caddy):/data/caddy/pki/authorities/local/root.crt /tmp/root.crt && sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain /tmp/root.crt
# Linux
$ docker cp $(docker-compose ps -q caddy):/data/caddy/pki/authorities/local/root.crt /usr/local/share/ca-certificates/root.crt && sudo update-ca-certificates
If Symfony is generating an internal redirect for an https:// url, but the resulting url is http://, you have to uncomment the TRUSTED_PROXIES setting in your .env file.
For more details see the Symfony internal redirect documentation.