I only have read access to my brand new G Drive R-Series from my MacBook Pro, MacOS High Sierra 10.13.6. The SSD disk is formatted with Mac OS Extended, I just received it, plugged it in and cannot write. Any help is highly appreciated!
So the device was formatted from another computer? If there is no important files, you can try to reformat the device again. Since it is SSD device, use APFS format instead of HFS+ format.