Transferring files from My Cloud to My Cloud EX4100

Hi, Could you please let me know how I can transfer my files from an old My Cloud to a new My Cloud EX4100?
There is a video on the website that shows a button on for transferring files from MyCloud device to EX4100. But, this button does not exist in my account. The video is for 2017. I believe this button is removed and there should be another way to do that. Please advise.