HPE Fast Fault Tolerance Memory Configuration with ML 350 G10

I would like to use HPE Fast Fault Tolerance with a new ML350 G10 with DUAL Intel Xeon 3106 processors.  Right now I have eight 16GB Dual Rank memory modules specified (four per processor).  I have studied the Memory RAS Technologies document here,

https://psnow.ext.hpe.com/doc?id=4aa4-3490enw.pdf

It says, "There must be a minimum of two ranks on each populated channel. Furthermore, only HPE SmartMemory in x4 organization can be used. "

I don't know what "x4 organization" means.  I also went to the memory configurator, but it only shows you how to populate the server memory with no consideration for fault tolerance.

Any help would be appreciated.