Custom field in order confirmation mail to administrator

-- url of the page with the problem -- : catalogo.uniontrade.info
-- HikaShop version -- : 4.4.2
-- Joomla version -- : 3.10.2
-- PHP version -- : 7.3.31

Hi,
I've added some custom fields in the registration form (see attached). How can I display the field 'user_tipo_attivita' in the mail I receive when a order is sent? I need it because it change the way I answer, and now I always have to go to details page of the customer.
thank you
Elena

Hi, thank you for your answer, I tried to do what you suggested but I still get no results.
As you can see in the screenshot I added the {LINEVAR:USER.user_tipo_attivita} code in different places but the mail I receive (attached) don't show the field (I should see 'BUBBLE TEA SHOP' in this case, 3 times...)

Sorry to bother you but I really don't understand what I'm doing wrong.
thank you
Elena

Thank you so much, now it works fine!