23:26-32
We then come to the Day of Atonement. This is the day when atonement was made for their sins. The emphasis of the chapter is on the people doing no work, and very severe punishment for anyone who does do work. To put in gospel terms, we contribute nothing to our salvation, we are to put our trust completely in Christ and His work. If we do otherwise then we have no part in the gospel. Paul took a very severe line on this in his letter to the Galatians.
23:33-36
Few details are given for the rationale behind this festival, though the term “tabernacles” (or tents) may well arise from people living in huts during the harvest. Yet again the people are not to work. No details are given on the nature of the offerings, except to briefly mention “food offerings”. More details are given in Num 29:12-38. Zech 14:16-19 does talk about all nations celebrating the Feast of Tabernacles.