Hello @ironhak
I’ve used this nextcloud app: Community Document Server - Apps - App Store - Nextcloud
This is not our app. The Nextcloud team forked one of our older builds and re-wrote its source-code. So, we can’t troubleshoot this app.
We recommend using our official app https://apps.nextcloud.com/apps/onlyoffice and connect your Nextcloud portal to stand-alone Document server (self-hosted or Cloud version).
More information about the situation is here: Community Document Server app in Nextcloud 18