How activate flow features

I attended the excellent Knack webinar titled Knack Flows Training and I am trying to test flow.
I started with a simple flow that insert a record in Log_flow table when a record is inserted in table_a.
My trigger action is set as Record Created with no condition.

As 2nd Step I have a Create record

It seems simple nevertheless I start the flow but it never triggers! I tryed also with a Record Update trigger with the same no-trig result!
I reviewed the recorded webinare more than once and it seems I configure trigger as expected.
What I miss? I have to enable somewhere the Flow functionality?

EDITED: I have a PRO plan.
EDITED: I tried a scheduled flow and it works fine! So what I miss into the triggered flows?