Starting March 6, 2024, Amazon Appstore is no longer be available for download from the Microsoft Store on Windows 11 devices. After March 5, 2025, Amazon Appstore on Windows 11 and any apps downloaded from it will not be supported.
[Using the Amazon version in an Android emulator here]
It's recommended to regularly backup the song library; you might need to reset your computer, hardware failures or reinstall the app etc.
In iReal Pro, click the Settings icon (at the top of the Library),
scroll down Settings and click on Backup Songs and Playlists.
A backup file will be created and Windows will automatically save it into your Windows Downloads folder. A brief message from Windows indicates what it has done, Click Show in folder to find your file.
(You might like to store a copy in OneDrive (or similar), move it to your Documents folder or email it to yourself as your Downloads folder may not be automatically backing up to OneDrive. This is a precaution to keep your files safe.)