You may toggle between the Keyboard + Mouse combination and the Controller by pressing F6 on your keyboard.
The preferred controller type can be set under the Main Menu Options - the Controls section, to be precise.
Should you have any issues with the above controllers, you may want to try configuring your controller under Steam Big Picture Mode.
Please note that Pure Farming 2018 natively supports the Xbox One, Xbox 360 and the Logitech G Saitek Farm Sim controllers for Windows along with other XINPUT controllers. Steam controller and other controllers may not function correctly with the game.