To connect your business account with InstaPlus you must have a business account created on Instagram.
Please follow below-given instructions to connect.
Go to App admin --> InstaPlus Shoppable instagram --> Connected Accounts
You will get 2 options to connect with Instagram Business Account.
1. If your Facebook business account page is connected to the Instagram page then you can log in with Facebook. Click on Connect to Facebook Account and it will ask username and password. Log in to your Business account. After login to your Facebook page, when you click on the Facebook business page you will see the Instagram business page by default displayed there.
Note: At a time you can connect with one platform either Facebook or Instagram.
2. If your Facebook business account page is not connected to the Instagram page then you can direct login with your Instagram business account by clicking on Connect Your Instagram Account.