Modification of a dedicated prestashop module

I have a dedicated module for prestashop whose task is:

send emails to a specific group after the order is paid, but only if the person ordering has a specific group.

Using this configuration:

$groups = [

5 => [4],

];

5 - means the ID of the group to which the email will be sent, if the group 4 will place the order

I don't understand why mine doesn't work, the email doesn't reach group 5, please offer ;)