Hey @Martina Natale
I understand that it is best to take courses and certifications with your personal address, since when you leave the company you may have difficulties recovering your account. In cases of partnership, you can associate your personal address that has your certifications to the company, and with that it receives the benefits, in case you leave, you can easily take your account to another company.
however, when starting the exam registration process, there is an option for discounts.
at the end of the page...have this option
where you can enter another email that has a voucher to be used. this email will be verified, sent a code that you must enter in the verification screen. and if there is an associated voucher, it will be released for use.
I hope this works for you, and good luck with your exam