Ex4100 pro works fine from Android but how do i add it to my iMac and macbook pro

My Cloud OS 3 Personal & Network Attached Storage My Cloud EX Series
2

Did you check the thread immediately below the one you just posted…?

You haven’t said whether you are trying local or remote access, or whether you have read the user manual.

You might also try the more appropriate forum, just in case it’s specific to the 4100:

https://community.wd.com/c/network-attached-storage/my-cloud-expert-series