Complete install on mdadm raid on raspberry pi 4

Hello
I am very new to this
My setup
Raspberry Pi 4gig 4B+
Quad Sata Hat w/ 3 x 1TB SSDs in RAID0 1 x 750gig HD(not setup)
mdadm Raid0 mounted under /media/pi/

What I would like to do is install Nextcloud 20 on the RAID0
I have never done this before so not sure what I need to do
please help me get this setup

Thank you

Just think if you need RAID 0 (striping) or RAID 1 (mirroring) and set it. Have similar setup, you can see it here Optimal hard disk setup on Ubuntu 2 x SSD (Raid1) + 2 x HDDs (Raid1) few commands are also in a tread --> Optimal hard disk setup on Ubuntu 2 x SSD (Raid1) + 2 x HDDs (Raid1)