Server System Admin (Ubuntu)

I have a server that I got from [login to view URL] KS-4 Intel Atom N2800 2c/4t 1.86GHz SoftRaid 2x2TB NOTE: 2X2TB I did a custom install of Ubuntu18, I installed without RAID 1, it is not RAID 0. I used the following guide up to step 4... Now I'm Stuck! [login to view URL] I need you to set the partitions so that my website has access to 3.6TB (estimated) of space and NOT just the 1.6TB with a mirror on the second 2TB HD. Then I need detailed, specific, step-by-step instructions on how to do this setup myself in the future on identical boxes ...I have about 10 boxes I will need to do this to in the future.