Best Disk format for ReadyShare?

Hello

I have a Nighthawk CAX80 and want to use the Readyshare with a 1 TB SSD. I formated it as NTFS and GPT and the device is not recognized (web page says "No Disk"). I tested an Ext4 I had around and also it did not work (kind of expected that)

I saw somewhere that ReadyShare is quite sh#$@ and does not support all the formats that the documentation says it supports... what is the "preferred" format? (or the one that works most of the time)