There’s a README with information on how the projects are structured. To run them you just open the relevant project in the matching version of Godot (Godot 4.5+ with either the .net version or regular version) and press the run button.
Viewing post in Speech Balloons Example Project comments
The dialogue balloon works in the project you provided. The problem is making it work in another project. For example, I already have Dialogue Manager installed as an addon. I can use the default one, but I need specific instructions on how to get the Speech Bubble Balloons to work. I'm a bit confused about what exactly I should move from your project to mine.