Background context:
We would like to have an automated message sent to a specific channel in Slack, when a specific issue(we filter it with JQL and validated) is transitioned from TO DO to IN PROGRESS.
Current situation: Though the integration has been set, I have no clue why the automated message are not sent into the specified channel.
Here are the step by steps I made earlier:
I got into this Automation page, it explained the step by step very well.

The next step is how do I get this webhook URL, I follow the link provided in here.

Getting into the provided link, do a simple step by step in this page, and save settings.

As I go back to my Slack channel, I see the integration has been addded.

Then I tried to move a specific card that are matched via JQL that has been previously defined in automation page (first image above), There are no upcoming message sent to the channel.
Is there any way to solve this issue? or other alternative to do what I look for sending automated message when a issue card transitioned from TODO to IN PROGRESS?
Tuspecting issue might be in "configure an incoming webhook" as it is stated that this is a legacy custom integration/an outdated way to integrate with slack.