@brebDev Aspose.Words.Shaping.Harfbuzz uses P/Invoke technology for invoking unmanaged functions from HarfBuzz.
For Windows platforms no additional efforts are required for installing HarfBuzz because Aspose.Words.Shaping.Harfbuzz already includes compiled HarfBuzz library.
For other systems, Aspose.Words.Shaping.Harfbuzz relies on already installed HarfBuzz library. For instance, many Linux-based systems have HarfBuzz installed system-wide by default. If not, there is usually a package available for installing via package manager.
For example in the clear Ubuntu Docker image it is required to additionally install Harfbuzz using command like this:
RUN apt-get update && apt-get install -y libharfbuzz-dev