Via email?
Yoga Studio X website says: contact us at contact@yogastudiox.com, then as part of the registration process in your app, you ask for an email with exactly the same email domain.
You would need to manually verify though. But I think it's worth it. Steps:
- deny any generic email domain address in your registration form (e.g., gmail.com, yahoo.com, etc.)
- whenever a new "company" registers in your app, you'll get a "needs approval" notification. You quickly check if the email they submitted corresponds to the "official" email of the website of the business they claim to own. You could even automate this. The user will receive as well an email to confirm their email address