If a PBP 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 PBP file.

Find a PBP 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 PBP file.

If you don't know the application which function as PBP file opener then try to search for 'PBP wiki', 'application to open PBP file' or 'open PBP file' queries in the search engine you like.

If you know the application which can open PBP file then run it and see if there is a File->Open main menu option in the application.

If a PBP 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 PBP file in question in Windows OS File Explorer and double click on it to launch the corresponding application.

Convert to pbp file