Why am I seeing 'Store Coming Soon' message after payment?

Shopify Discussion
2

If you can log into admin, make sure the Password protection is Disabled.

  1. From your Shopify admin, go to Online Store > Preferences.

  2. Go to the Password protection area.

  3. Uncheck Enable password.

  4. Click Save.

Also, you can try to get on the chat with the merchant team and let them look into the account.
https://help.shopify.com/en/questions#/contact/chat