This stuff needs to come with serious health warnings.
Actually if you go to the product page and look at System Requirements you won't see windows 10 listed.
https://www.stardock.com/products/thememanager/
You didn't say what the second program is you downloaded. To apply any theme you need the required software. Example: If you wan to use a WindowBlind you need to install WindowBlinds. If you want to customize the full Windows 10 using WindowBlinds you also need to install start 10 along with WindowBlinds. Not all software included with Object Desktop is compatible with every OS so best to check out the product page.
If you don't receive an answer on this thread it would be best to submit a support ticket. Support is closed on the weekends. Only submit one ticket and wait for an answer. If you submit additional tickets with will be put back on the bottom of the list.
https://esupport.stardock.com/index.php?/Tickets/Submit