It’s been a while you have been asking how to run NextCloud on Helios4, so finally we just published a tutorial on our wiki on how to install NextCloud 13 on a Debian 9 Stretch install.
You will need the following before starting:
You should have Debian 9 Stretch running on your Helios4 (Ideally the latest image). You can refer to the install page for instructions.
You should have setup your storage. Refer to the new mdadm page for instructions on how to setup a RAID array.