Extract v1.18 to the target folder (eg: F:\Eronest)
Extract the DLC to the same target folder (eg: F:\Eronest), allowing all overwrites.
Launch the game.
I recommend not using saves from a previous version (including from before any DLC being installed) to prevent any issues (such as the language switching not working)
Also keep in mind that the language switching requires a game relaunch before it takes effect.