Encrypting Macs with Filevault

[DalekSec]

How does everyone managed encryption on their Macs? I tried following Apples guide: https://support.apple.com/en-gb/HT202385 but from what i've read step 3 is no longer valid in High Sierra as there is no master password. So it makes the guide null!

 

I've found in our MDM (Mosyle) how to switch it on but i'm not 100% sure how the key system works on here! Years of using bitlocker has left me confused at a different system!