Invitation to the Saas platform with payment

I am looking for some examples of companies/ websites who are using the model below:

  1. The company A is using the Saas platform for the assesment (paying for it).
  2. The company A wants to invite other companies (supplier B, C, D) to the platform to be assessed (they need to pay as well).

I am interested how the payment is communicated to suppliers B, C, D (other companies). Currently I am working on the customer journey, where this information is communicated, but not that straight forward (smaller font, at the bottom of the page), which bring friction later in the process, where we ask them to pay.

Do you know any examples?

Thanks!