When it's finished, find the menu bar at the top and go to Extensions -> Manage Extensions. Once you fill those two fields, click on Clone and wait until the project finishes downloading. In the new panel you have to fill two things: You will see four big buttons, click on the first one: Clone or check out code. From now on, you should launch Spore through the launcher. In order to use the ModAPI SDK and the mods you generate with it, you will need the ModAPI Launcher Kit, which you can download here.
Once you have all that selected, click on Modify and wait until it's installed. If you want to do mods related with graphics, you will need this to interact with DirectX. Ensure the MSVC v142 and Windows 10 SDK options are checked.
When you select this option, on the panel on the right there are some other options you can check. For the ModAPI SDK, you need to check the following: You can download it here After the installation, the Visual Studio Installer will open, allowing you to choose what features you want.
You need to download Visual Studio 2019 Community, which is the free version.
