[Most Gentiles stop here as if that is the end of the instruction and that is ALL they are required to do. Funny enough, the ones who proclaim this actually don't even follow this instruction by all practical purposes.]
In fact, this instruction is only the beginning. It was the simply MINIMUM requirement for all Gentiles to enter the Messianic Synagogues and enjoy fellowship with believers in Messiah Y'shua (Jesus). The next verse clearly implies that once they enter, they will learn about the rest of what God requires of Gentile believers in the Jewish Messiah...
Acts 15:21 - "For from the earliest times, Moshe (Moses) has had in every city those who proclaim him, with his words being read in the synagogues every Shabbat (Sabbath).
The Law most certainly applies to ALL Jews and Gentiles. True, we are not saved by keeping the Law, but by God's grace, but we are saved to KEEP the Law and live lives that honor God.