Hello !
You should be able to install the app by opening the Microsoft Store on your PC, clicking on Library, and looking for your app.
Then, click on the blue Install button.
If the HEIC Pro app does not appear in the Library section, click here to directly access the app's page in the Microsoft Store : https://apps.microsoft.com/detail/9PDKQVHQZNFM and click on the Install button.
Please let me know if you have any other question !