From my understanding we need a test that compares two independent binomial proportions (placebo group/ leronlimab group), to compare whether the observed difference between placebo performance and leronlimab group is stat sig.

As far as I can see, your test only considers the leronlimab group in itself (like when tossing a coin 66 times and getting 60 times head, where the probability of head/tail is 50% under normal circumstances), not the difference between leronlimab and the placebo control-group (?), which is what we need, since despite the binary outcome you can't assume that the probability of dying/living is 50%.

But I'll let the guys who are actually proficient with this stuff weigh in...