Formatting a DualDrive G0 Type c - help please

I have just bought a Dual Drive GO USB type C to copy photos back and forward from my Android smartphone to my iMac (as advertised) However whenever I insert into either I am asked to format the USB drive before it can be used with that device. If I do that then it is unreadable on the other device.
For example if I format it to read the android phone the iMac will not recognise it

Hi @Terry2,

Have you opened a Support Case? If not opened, for more information, please contact the SD Technical Support team for best assistance and troubleshooting: