If your merchants see an error message like below, the most likely reason is that you (the marketplace admin) have not properly linked your Stripe account to your marketplace. If you have properly linked your Stripe account, merchants should not have any issues.
To make sure that you linked your Stripe account properly to your marketplace, You can view the step-by-step guide on how to connect your Stripe account to your marketplace in the Payments section. You can also find the guide entitled ‘How do I connect to Stripe’ that is located in the Stripe setup page, which can be found by clicking 'General' from ‘Settings’ menu, then click 'Payment Methods', and then click 'Link Account' button for Stripe.