your code relied on broom::tidy which you hadnt declared.
You can do this
iris %>%
group_by(Species) %>%
summarise(across(.cols = Sepal.Length,
.fns = list(min=min,
q1 = ~quantile(.,.25),
median=median,
mean=mean,
q3 = ~quantile(.,.75),
max=max),
.names ="{.fn}"))