Connect Instagram Business Account
Go to Settings > Channels from the left sidebar open Instagram and Click on Connect with Instagram button.
It will redirect you to the fb login page. Login your FB account by entering correct credentials.
You will see this screen after entering correct FB credentials. Click on Continue as button.
Select your account that you wanna give access.
Choose the page that you wanna connect.
Select the insta account that you wanna connect to.
Review the permissions and click on Save button.
Your account is now connected. Click on Got it button.
Select the page from drop down and click on Connect.
Your account is successfully connected.
Don't have an Instagram Business account?
Here is a guide on how to connect your Instagram business account with your Facebook page.
https://help.instagram.com/570895513091465
https://help.instagram.com/570895513091465