To inject x64 DLL's into x64 processes, you should use x64 pointers. But as you are using handles instead of pointers, the compiler can take care of its length instead of you. So compiling this ...

wchar_t dllPathAndFilename[MAX_FILE_PATH_FILENAME_COUNT] = { 0 }; // contains the full path + filename of the injected .dll wchar_t processPathAndFilename[MAX_FILE_PATH_FILENAME_COUNT] = { 0 }; // ...