If you had purchased Mac version serial number , you cannot use it to activate on Windows computer.
However , you can opt for platform swap for serial number , so that you can use the serial number to activate on your Windows computer .
This is one time process and the serial number will not be changed back to Mac again.
Refer below like :
https://helpx.adobe.com/x-productkb/policy-pricing/exchange-product-language-os.html
For more info , you need to contact Adobe Support : they will check and assist you accordingly as per terms and conditions.
Click on Still need help button and select Chat option :
Contact Customer Care