FSW 6th July 2022: Ranking vs CRS

[lemongrass1]

1. There was draw for FSW today (6/Jul) and about 1500 were selected.
2. It mentioned "Rank required to be invited to apply: 1,500th or above"
3. CRS lowest score was 557.

Query: what is the difference between point 2 (rank) and point 3 (crs score) ?

How to calculate the rank ?