TLDR: 96 GB (2x 48 GB) unofficially with current ram modules, 64 GB (2x 32 GB) officially with current ram modules, 256 GB (2x 128 GB) officially with a theoretical future ram module.
The CPU officially supports up to 2x 128 GB modules for 256 GB total.
However 128 GB modules don’t yet exist. The largest modules that do exist are 48 GB for 96 GB total.
However the CPU officially only supports modules that have capacites that are powers of two. 48 GB is not a power of two, which means the largest modules that currently exist and are officially supported are 32 GB each for a total of 64 GB.
In practice however 48 GB modules do work fine and many users do use them.
The quote you’re mentioning is probably referring to the maximum that you can put in each slot if you stick with modules that are officially supported and currently available.