Hello!
I'll tell you how to launch the main game and its DLC. Once the game is installed, click Play. You'll then have two launch options: Sakura - Option 1 - Main Game "Sakura"; Sakura - Option 2 - DLC "Sveta Sky AI".
Also, if you don't have this launch option, you may have checked the box to avoid asking each time. In that case, click the gears on the right, go to General, and then ask at launch.
Also, if you don't see launch options, there are two options: 1) you haven't purchased the DLC; 2) you need to verify the integrity of the files: click the gears again, then go to Installed Files, and then Verify File Integrity.
That's all there is to it. Launching isn't that difficult. If you have any further questions, you can always email me at: [email protected]