2017 to 2020 appliance migration clarification

https://www.novell.com/documentation/zenworks-2020/zen_upgrade/data/b1g4yqtl.html   Step 2 says to attach the vastorage disk before power on.  Then step 5 says to attach the zenworks content disk while the appliance is running?  Is this correct?  Can I get some clarification on step 5?

When I migrated from 11 to 2017, the docs said to attach both disks before power on.  Just trying to make sense of this.

Thanks!