If you know the Mac OS application which can work as BAK file opener you can choose the 'Choose Application.' option in the error box to associate the file extension and open BAK file in it.If a BAK file is not opened in a Mac OS application and you instead get a 'There is no application set to open the file' error message you can click on 'Search App Store' in the error dialog and Mac OS will show you applications compatible with BAK file.Find a BAK file in question in Mac OS Finder and double click on it to launch the corresponding application.Install the application you found and check if it can open BAK file.If you don't know the application which function as BAK file opener then try to search online for 'BAK viewer', 'application to open BAK file' or 'open BAK file' queries in the search engine you like.If you know the application which can open BAK file then run it and see if there is a File->Open main menu option in the application.If a BAK file is not opened in an application and you instead get a 'Windows can't open a file' error message you should try looking for an application which can open the file in question.Find a BAK file in question in Windows OS File Explorer and double click on it to launch the corresponding application.

Bak file viewer online