One NextCloud instance for many organisations

I am working as a volunteer of many organisations. I think some of the organisations might be helped with NextCloud.
Is it safe to set up one NextCloud instance on a manager’s domain and create a URL organisation1.com and organisation2.com which are using the same NextCloud instance.
Users of organisation1 don’t know which people are connected to organisation2.

Is that safe? Or do I have to setup NextCloud for each organisation separate?

Regards,
Guido

If you have separate instances, there is always a better separation. In theory, you can separate groups within Nextcloud that they don’t see each other (unless there is a bug), some things are really difficult to handle, e.g. there is no group quota, so you can’t say how much storage an organisation is allowed to use. Two separate setups, the data-folder in different locations, put different quotas => done. Some organisations use different apps that you don’t want to give everyone?

With different setups, you are much more flexible. You can customize them for each organisation, provide different services, and some day you might want to migrate one organisation to a different machine. Big disadvantage: You need to manage all clouds separately, e.g. running upgrades several times.