You might wanna check Nextcloud/Spreed.me install script Debian i made a script that runs the whole instruction for you (on debian 8.5). The only issue with the script is an error when entering a spreed.me chat room i haven’t figured out yet.
The errors i got with spreed.me most of the time are typo’s in one of the config files. In this case i would gues in the spreedme-server.conf