Zakeke is a visual design tool that always works in RGB mode, just like any other on-screen tool. All previews and outputs are in RGB.
However, Zakeke offers Pantone/CMYK mode, which allows you to display and manage colors using Pantone or CMYK codes.
For CMYK, you can also choose to use an ICC profile. In this case, the UI remains in RGB, and the profile is embedded in the final PDF to allow the printing machine to automatically convert colors during printing.
For full details on how to set up Pantone/CMYK mode, create palettes, and manage output files, see the Pantone/CMYK Mode Guide.