These texts are intended for students who already have completed Adler, or a similar course of study. Some are available in a bilingual version, so that you can study them in audio without needing to look at the printed text - ideal for studying while communing, or walking in the park. Review texts in audio, in Latin only, are also provided.
A couple of the texts at this level are in Latin only, but are very simple. Of these, the most famous text is Corderius' Colloquia. For hundreds of years, every student of Latin was expected to master these.
In a sense, this level is the most important - to gain fluency, you need to listen to, and read, a large amount of material that is not too difficult - these texts were carefully designed for just this purpose. Take them, one at a time, and listen to them over and over, until you understand them perfectly.