If you search for "exceed" in the doc, further down, you will find this passage. So, I think they are talking about vmdk size, instead of lun/datastore size. If your vmdk size is smaller than 6 GB, you will be ok.
Specify a VMxpath to a virtual machine
that has a VMDK size of 6GB not to exceed
50GB datastore as a result of eight VMDK
cloning operations done by VAAI Full
Copy tests.
There is a table in "Allocating LUNs" section that shows a list of luns needed, and their size.