Follow these steps to connect your Instagram account to your Meta Business Suite
1. Open business.facebook.com in a new tab
2. Click on Settings in the bottom left sidebar
3. Go to Accounts → Instagram Accounts (Make sure you're going to Instagram Accounts and not Pages)
4. Press Connect Assets, select other business assets and select your ad account
It's VERY IMPORTANT that you're on the Instagram accounts directory under Accounts and not the Pages directory under Users.
Then click Connect assets and press Other business assets
Next, select your ad account you're using in intellijend
Then refresh the page in intellijend and your Instagram account will appear.