If I understand correctly, you need to understand the structure of the Delphi project and how Forms and units work together. You cannot just select some files and expect to be able to pass them to the compiler.
You also need to set the path to the library / components / files used so that the compiler can find everything it needs, starting with the dpr project.
I would recommend that you first try to start the project from the IDE, and then, as soon as it starts, you can try it from the command line.
François
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