How to do an attack while liberating

[Arikania]

I'm stuck in the tutorial of the demo, playing with keyboard + mouse.

I see a bar at the bottom run empty, and when it is empty, my instructor attacks. So I press 'R' to start liberation, and then 'Z' to do an attack.

Sometimes, a red circle appears when I press 'R', but at those times, 'Z' is unresponsive.

What am I supposed to do at which times in that exercise?

[VertVentus]

For the tutorial prompt again (5:59),
https://youtu.be/dfszvhfXe_g?list=PLqaFPJxwRQWyvyVR6_lb22NlyAkSzag_5&t=360
When you press R to Supress/Liberate, it changes whether Sari has her hat on (Suppressed, defensive mode) or hat off (Liberated, attack mode that drains the MP gauge at the bottom).
You want to attack 6 times with Z while Liberated, before the MP gauge depletes and forces you into Suppressed.
When you are Suppressed, receiving a melee attack will allow you to fill that red circle by holding R. Release it when it's fully filled counterclockwise to unleash a counterattack that drains MP to hasten when you can re-enter Liberated mode. Projectiles can't be countered, but do have circles you can press R to to dodge them.