Can’t connect Arduino to Macbook

I cannot get my arduino uno to connect to my MacBook Pro. The MacBook is old, but still fully functional (I don’t know the model). I tried to connect the Arduino via USBs, but no matter how many times I try, or how many different ports on the computer I use, it will not connect.
The green light on the Arduino always turns on.

Do I need an adapter or do I need to retry anything?