How do you want to access the files? Browser, SMB, NFS, iSCSI, app like syncthing?
If it were mine, I'd put all the drives in RAID 10, install Proxmox, and either use its containers or create a VM to run docker and give it a big virtual disk.
But the dell controllers aren't very flexible with resizing the RAID. If you want flexibility, consider flashing it to IT mode if possible and then doing zfs, software raid, or LVM groups.