I beat the game with Jill three times and in all of them Tyrant didn't show up.

First time I beat the game I saved a lot (like +20) and with a time of 2:53. I also saved Chris;

Secong time was using special weapon and saved 01 times. I also saved Chris.

Third time (file attached) with 1:04 with 00 Saves. I didn't save Chris (everyone else dies) and I got the rocket launcher, but even so Tyrant didn't show up in the heliport.

Is it possible to make Tyrant appear in the heliport with Jill or is it just gonna happen with Chris?

For the Tyrant to appear in the helipad, you need to save both Barry and Chris. Only saving one of them is not enough to trigger the Tyrant fight.

How can I save Barry? He always dies after that conversation between Jill and Wesker.
(image attached) Does it have to do when Barry asks you to wait while he geats another rope?
I didn't wait for him in that snake's room.

Yes, you have to wait for Barry to return with a rope to gain his trust.

That can't be because I only saved Barry and got the heliport Tyrant. Not sure if that's the same with only saving Chris though.

So probably to have Tyrant in the Heliport it is neessary to save, at least, Barry.

I just beat the game with Chris and Tyrant appeared after I saved Rebecca.

You need Barry alive (wait for him to get the rope AND don't let him go first during the Cave map)

As long Barry make up to the Lab, he will activate the auto-destruction and will also trigger the extra Tyrant battle at the Helipad (you can let him die there too, iirc)

IMO, this game has a much more interesting way in dealing with Barry than RE Remake.

For Jill you need to save Chris and Barry to see Tyrant a second time.

For Chris you need to save Chris and Rebecca.

For Jill you need to wait for Barry to return with a new rope in the Snake room, you meet him again in the sewer, He will ask you two questions, you answer yes to both of them, that's how you get the good ending. (I think he can technically die here too? I might be wrong though, it just makes sense if you were too slow following him).

I don't think he can die in the caves. I tried with both options when he asks whether you want to go first, yes and no, and, he survived both times.

I completely missed that he only appears when you wait for the rope though. I almost went down instead of waiting, and was surprised that he shows up again, as I thought he intentionally drops the rope...