I downloaded and installed it. And I pinned it without issue. Here is how I pinned it. After installing it, on my Start 11 menu (Windows App style), on the right column, there is "Recently Installed" list and "Professional Numerologist is listed there, right click on it and select pin to Start11 select which group to pin. Refer to my screenshot below.

Thank you,
Basj,
Stardock Community Assistant