1st step:
- open your Mint software manager (if you don't know where to find it, type
sudo mintinstall
in your terminal and press enter)
- search for steam-devices and install the package (alternatively you can install it via apt, if you are familiar with it)

2nd step:
- open your terminal and type
cd ///lib/udev/rules.d
- type
sudo nano
(you can use a different editor, if you prefer so)
- copy the following text and paste it into the blank file (remember that you will need to press ctrl+SHIFT+v within the terminal to paste):
SUBSYSTEM=="usb", ATTRS{idVendor}=="28de", MODE="0666"
KERNEL=="uinput", MODE="0660", GROUP="games", OPTIONS+="static_node=uinput"
KERNEL=="hidraw*", ATTRS{idVendor}=="28de", MODE="0666"
KERNEL=="hidraw*", KERNELS=="*28DE:*", MODE="0666"
KERNEL=="hidraw*", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="05c4", MODE="0666"
KERNEL=="hidraw*", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="0ba0", MODE="0666"
KERNEL=="hidraw*", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="09cc", MODE="0666"
KERNEL=="hidraw*", KERNELS=="*054C:05C4*", MODE="0666"
KERNEL=="hidraw*", KERNELS=="*054C:09CC*", MODE="0666"

- save as:
99-steam-controller-perms.rules

3rd step:
- type:
sudo udevadm control --reload
- type:
udevadm trigger
- plug in your controller,
if you need any more updates, steam will now tell you and lead you through it.