Project 3 weekly retention analysis case study.

Hi Team, I feel difficulty in solving the case study below. My understanding: 1.user signedup cohort means--> i have to find the distinct users and extract week from created_at column by grouping week from "users" table? retention users means--> i have to find the distinct users and extract the week from "occuredat" column where the eventtype should be signedup_flow and engagement from "events" table? Then to find the retention rate on weekly basis, i should find count of retention users/ count of signedup users? Please correct my understanding if am wrong and I was confused while writing query. Please help me on the same.