I can't troubleshoot your exact issue, as you seem to not see what is happening in the background and are relying solely on error pages. We need to get to the container logs.
So, I removed all of the containers, deleted the data and database folders, re-made the folders, and re-deployed everything. Now NOTHING works and I can’t get nextcloud to re-do its initial setup.
Did you remove the old containers and volumes?
Clean up unused containers, networks, images, and volumes
docker container prune
docker network prune
docker image prune
DANGER ZONE LOSS OF DATA IF YOU DONT HAVE BACKUPS
docker volume prune
That will give you a clean environment to start over with your compose files.
If youre still having issues, inspect the live container logs to find the errors.
docker container logs --follow
Then post the errors.