Samsung Galaxy Tab A6 help

Hey all,

I have a Samsung Galaxy Tab A6 and I'm trying to transfer books from ADE on my MacBook Pro to the ADE app I downloaded on my Tab 6, but ADE on my computer does not recognize my Tab 6 as a device. I have my Tab 6 and computer connected via the USB charging cable, but my computer doesn't even recognize my Tab 6, or at least I don't think it does because the device does not show up in finder.

I'm just trying to read ebooks I've borrowed from my local library! Looking for help remedying this issue.