Nextcloud using Docker Compose Behind Caddy. I've broken something but can't figure out what

I’ve been trouble shooting getting both Nextcloud and Wordpress up on a VPS behind Caddy as a proxy. At one point, I successfully set up Nextcloud and was all the way in. I reinstalled Ubuntu as a part of my troubleshooting on the Wordpress side, but was confident I could recreate my Nextcloud set up as I had (I thought) cataloged all the commands I entered into the terminal.

Well I now have Nextcloud up behind a Caddy proxy and can access the installation page in my browser, but now I keep getting an error when attempting to complete the install and create a an admin account.

I would appreciate someone reviewing my files and letting me know if there are any glaring issues. If someone has a better compose file they’d like to share that works with Caddy, I’d also welcome that. I’m a novice at all this, so please be patient with me if I don’t fully understand.

Here is my set up with passwords changed for privacy:

Docker network up caddy_net

Docker launched caddy in a user/docker/caddy

Nextcloud launched in user/docker/nextcloud

.env file in user/docker/nextcloud:

MY_DOMAIN=private.org
DEFAULT_NETWORK=caddy_net
MYSQL_ROOT_PASSWORD=password1
MYSQL_USER=zachary
MYSQL_PASSWORD=password1

Docker-compose.yml in user/docker/nextcloud:

version: '2'

volumes:
    nextcloud:
    db:

services:

    db:
        image: mariadb
        command: --transaction-isolation=READ-COMMITTED --binlog-format=ROW
        restart: unless-stopped
        volumes:
          - db:/var/lib/mysql
        environment:
          - MYSQL_ROOT_PASSWORD=
          - MYSQL_PASSWORD=
          - MYSQL_DATABASE=nextcloud
          - MYSQL_USER=nextcloud

    nextcloud:
        image: nextcloud
        container_name: "nextcloud"
        hostname: "nextcloud"
        links:
          - db
        volumes:
          - nextcloud:/var/www/html
        restart: unless-stopped

networks:
    default:
        external:
            name: $DEFAULT_NETWORK

According to my records, last time I was able to log in with this information:

Admin username: Zachary
Admin password: password2

Database User: root
Database Password: password1
Database Name: nextcloud
Database Host: db

I’m not sure what I broke. Any help is appreciated, thank you!