The folders are disappeared when the WD (My passport) connected to the MAC

The folders are disappeared when the WD (My passport) connected to the MAC. I cannot find anything on my MAC computer in WD. But I can find that there are 500GB contents inside of this WD. What’s wrong with this?

What is the filesystem of your external hard drive?

Thanks for your question. I have understood the reason for this. The format of this hard drive is MAC OS extended and my current MAC system is Big Sur which does not recognize the format of MAC OS extended of the hard drive. So the solution is to use a lower MAC system to move the contents of the hard drive out and then change the format of this hard drive. That is.