It’s easy to copy your files and settings wirelessly from another Mac or PC to your Mac mini. You can transfer information to your Mac mini from an existing computer or from a Time Machine backup on a USB storage device.
You might need to upgrade the macOS version on your older computer before you can transfer the information on it—Migration Assistant requires macOS 10.7 or later, but it’s best to update your older computer to the latest version possible. If you’re not sure which model you have or want to find information about other models, see the Apple Support articles Back up and restore your Mac.
Copy files from a storage device. Connect the storage device to a USB-A port Transfer your information to Mac from another computer or device in the macOS User Guide and the Apple Support article Move your content to a new Mac.