(… وَلَوْ شَاءَ اللَّهُ مَا أَشْرَكُوا) (But if Allah had willed, they would not have associated.…): This is an issue which must be understood clearly. A disbeliever does not disbelieve because he is forced by Allah (swt) to do so. Instead, it is because Allah (swt) has handed him the reins of choice. Therefore, it is not our job to force others, nor do we burden ourselves with more than what our Protector has tasked upon us. We do not want to cut off necks, nor do we work to produce moulds (that everyone is forced to follow exactly). What we really strive for is to capture hearts. And this is the main point in this verse that we are discussing.
( وَمَا جَعَلْنَاكَ عَلَيْهِمْ حَفِيظًا ۖ وَمَا أَنتَ عَلَيْهِم بِوَكِيلٍ… ) (…And We have not appointed you over them as a guardian, nor are you a manager over them): Allah (swt) is The Guardian, and He is The Protector. However, you, O Muhammad are not any of these, but you are the one who sends reminders them. These points are the principles in calling others towards Allah (swt). The connection between this verse and the one which follows it is that both are concerning the methodology of calling people to Allah (swt), which has had its features specified in the Holy Quran.