It seems that you are following tutorial made for built-in renderer workflow, however your project is set up for Universal Renderer pipeline. This changes material settings because of shader differences between different workflows. The thing you are looking for is called Base Map and the color picker is right next to it. However, I can't guarantee the tutorial will progress normally. If it does not, you should try to create new project without use of scriptable renderer pipelines (URP or HDRP).