This is clearly an issue with your system: run permissions repair to start. Don’t forget to restart the the computer P.s. Reset NVRAM NVRAM is a small portion of memory used to store some settings for quick access on Mac system. Thereby, you can attempt to reset the NVRAM. Reboot your Mac and hold down the “Command + Option + P + R” key buttons. After resetting, you can retry to mount the drive on Mac. Sent from my iPhone using Tapatalk