Laravel 9 | Mailgun saying "Password is not set"

Question

I'm trying to setup an email system through my Laravel app via Mailgun, here's my .env file (sensitive info is replaced of course)

APP_NAME=Laravel
APP_ENV=local
APP_KEY=***
APP_DEBUG=true
APP_URL=***

LOG_CHANNEL=stack
LOG_DEPRECATIONS_CHANNEL=null
LOG_LEVEL=debug

DB_CONNECTION=mysql
DB_HOST=mysql
DB_PORT=3306
DB_DATABASE=***
DB_USERNAME=***
DB_PASSWORD=***

BROADCAST_DRIVER=log
CACHE_DRIVER=file
FILESYSTEM_DISK=local
QUEUE_CONNECTION=sync
SESSION_DRIVER=file
SESSION_LIFETIME=120

MEMCACHED_HOST=memcached

REDIS_HOST=redis
REDIS_PASSWORD=null
REDIS_PORT=6379

MAIL_MAILER=mailgun
MAIL_HOST=smtp.mailgun.org
MAIL_PORT=587
MAIL_USERNAME=postmaster@*****.mailgun.org
MAIL_PASSWORD=(provided default password for this domain)
MAIL_ENCRYPTION=tls
MAIL_FROM_ADDRESS=*****@gmail.com
MAIL_FROM_NAME="${APP_NAME}"
MAIL_DRIVER=mailgun

MAILGUN_DOMAIN=*****.mailgun.org
MAILGUN_SECRET=(I'm not sure what to put here, I tried the API key provided when I signed up and also the Mailgun password)

AWS_ACCESS_KEY_ID=
AWS_SECRET_ACCESS_KEY=
AWS_DEFAULT_REGION=us-east-1
AWS_BUCKET=
AWS_USE_PATH_STYLE_ENDPOINT=false

PUSHER_APP_ID=
PUSHER_APP_KEY=
PUSHER_APP_SECRET=
PUSHER_APP_CLUSTER=mt1

MIX_PUSHER_APP_KEY="${PUSHER_APP_KEY}"
MIX_PUSHER_APP_CLUSTER="${PUSHER_APP_CLUSTER}"

SCOUT_DRIVER=meilisearch
MEILISEARCH_HOST=http://meilisearch:7700

The error here is showing up pretty much no matter what I've tried changing. I can also supply the mail.php, controller, etc. if needed. I feel like it might be much simpler than that though.