It is confirmed that you can use it, but a license is required to remove the demonstration watermark.
You need to license the software to remove the demonstration watermark, please see our store: CADViewer – NextCloud (Subscription) – CADViewer Store , the base license is user based, where you in the admin interface can set which user has access at a given time.
License looks to start $499 for 5 users, but I didn’t dig into it. https://cadviewer.com/pricing/