Welcome @prosanelli , thank you for posting!
Could you please ask one of your company tenant’ admins to send you an invitation?
They can do so by going to the Auth0 tenant-> Settings → Tenant Members → Add Member. There, they would enter the email address that you will be logging in with (which can be the same as your own free developer one).
As a result, you will receive an invitation email with a link to join the company’s tenant.
Please let me know how it goes!