Section 2.2: Choices Up Chapter 2: Install Section 2.4: Download 

2.3 But first

2.3.1 Binary

Before you install Aubit4GL you may need to have installed other software

2.3.2 Source

The above will likely suffice for the binary installation.
But if you want to download Aubit4GL source and build it on your platform, because it is built in C, you will need the following as well:
You should get any development packages associated with these prerequisites. (They usually have a suffix -dev or -devel). These will provide among other things the necessary .h files. If you are a software developer you have probably installed these already.
How you get these and install them varies with different distributions. If your OS distribution has packages for your version of the OS, then use those in preference to downloading and compiling from source.
The above will all install any prerequisite packages in addition to your chosen application.
For applications like pdflib which do not come packaged with the OS distribution, installation will vary but you will expect to install most of them by
 Section 2.2: Choices Up Chapter 2: Install Section 2.4: Download