The Microsoft Store is an application store on Windows used to purchase, download, install, and license applications. For more information, visit: https://www.microsoft.com/store/apps/windows.
Your Creative Cloud subscription comes with Lightroom on desktop, Lightroom mobile (iOS and Android), access to lightroom.adobe.com, and 1 TB of cloud storage.
You can buy Lightroom from either Adobe.com or the Microsoft Store. It is the same app. However, it is not recommended to install both versions at the same time. Keep the version installed from the store where you purchased the app to ensure timely communication about updates.
The Microsoft Store will send you an update notification, and will provide you with the latest version of Lightroom desktop through the Microsoft Store.
Any Lightroom subscription that you purchase from the Microsoft Store is managed by Microsoft.
You can cancel your subscription using the Microsoft Store. For step-by-step instructions, see Microsoft's documentation for How to cancel your Microsoft subscription.
For billing issues or a refund, see Microsoft's documentation for Returning items you bought from Microsoft Store for exchange or refund.