Install the jmtpfs package: sudo apt-get install jmtpfs
Make a directory, any directory: sudo mkdir /media/myphone
Connect the USB cable
Unlock the android phone.
Swipe down from the top of the phone screen
You should see a notification "USB ..."
Tap that notification.
You should see a menu titled "Use USB to...", select "Transfer files".
On the linux computer issue:
sudo jmtpfs /media/myphone
fusermount -u /media/myphone