If what they sell is the open source Nextcloud, it is a horrendous product.
Its architecture is weird, with a proxy inside you can harden only by editing data inside a container that is volatyile by design (and has to be).
There are numerous issues opened on that topic, Nextcloud response is "live with it".
>>Brando+(OP)
We use it at work and everybody I asked loves it. I also recently moved my personal data to Nextcloud from Google Drive and it's been extremely pleasant to use