lsusb

Bus 010 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 009 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 008 Device 003: ID 04e8:6860 Samsung Electronics Co., Ltd Galaxy A5 (MTP)
Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The Samsung vendor ID we need is 04e8

sudo nano /etc/udev/rules.d/51-android.rules

SUBSYSTEM=="usb", ATTR{idVendor}=="04e8", MODE="0666", GROUP="plugdev

Also:

nano ~/.android/adb_usb.ini
and enter the vendor ID but add 0x in front, ex: 0x04e8

Restart:

sudo service udev restart

Also, important, enable USB debugging on the phone. Won’t work without. You’ll be prompted to accept the connection from the PC to the phone.

https://askubuntu.com/questions/632651/adb-devices-command-wont-detect-my-4-4-android-phone