Santander supports connecting both personal and business bank accounts to Coconut.
Unfortunately, the Santander mobile app can have issues, particularly when granting access to business accounts.
If you find that your business account is not available as an option to connect to Coconut from the Santander app, the following process can help (albeit slightly inconvenient):
First, delete the Santander banking app from your smart phone (you'll add this back later.
Now, complete the bank connection flow using Coconut as before.
This time, you'll be directed to the Santander website instead of the mobile app.
Login to the Santander website and complete the authentication.
You should be able to now select from all your accounts, including business accounts.
Once you've successfully connected the account, you can safely reinstall the Santander app on your phone.
Link to reinstall the Santander app:
Apple App Store | Google Play Store
An alternative to this would be to connect your Santander account over on Coconut Web instead of via the app. Once you've logged in to Coconut Web, head to your 'Bank feeds' tab > click 'Add account'.