I recently install Parallels on my Mac and it asked me if I wanted to install Windows, so I did. Now I can't activate it - it seems that you installed the Windows Enterprise editiion, which is a huge cost - why would you install Windows Enterprise on my computer, when I purchased Parallels for Mac Standard or not give me the option to decide which version of Windows was installed? I spent countless hours downloading everything and getting Windows setup, now it's forcing me to make a huge Enterprise edition purchase or do a complete new install and download and update everything. I can't tell you how angry I am with Parallels right now.
The Windows edition which gets downloaded will be Windows 10 Home Single language N, not an Enterprise edition. If you wish you can use an ISO to install the edition you need. You can continue to use Windows without activating as long it works but if you need genuine edition then you have to reinstall Windows in a new VM.