void initLibrary(int magicNumber, string email);

You have to call initLibrary right away when you loaded the library (created an object).
You can omit this function in your code but in this case you cannot modify dbf files.
Passing valid parameters allows you to use CDBFAPI in read/write mode.

Note: just in case you have to check that the library is loaded. If .dll is missing you will get an error later.

{
    CDBFapi dbf = new CDBFapi();
    if (!dbf || !dbf.libraryLoaded()) return;

    dbf.initLibrary(12345, "email@example.com");
    // your code
    dbf = nil;
}