Problems with Delphi 10.3?

[Pieter]

Please check the log file, and the following post:

Installation errors

Note that the new installers are more sensitive to handling errors during installation. Linker errors, SDK issues related to macOS, iOS, Android or platforms other than Windows will be detected. By default the installer will try to compile for each platform available in the IDE, whether or not it is properly configured. If you are not using the above platforms, you can safely ignore the error messages during installation. If you are unsure, please open the log file and check if there are message…

Most likely it's a compiler issue for macOS, which can be safely ignored. When Windows is compiling fine, the BPLs will be present in the IDE and the components can be used.