Prerequisites:

1. Instagram Professional Account — Convert your Instagram to a Creator or Business account (Settings → Account → Switch to Professional).
2. Facebook Page — Create a Facebook Page (any type) and link your Instagram account to it (Settings → Instagram → Connect Instagram).
3. Meta App — Go to developers.facebook.com/apps, create an app, add Instagram Graph API product.
4. Access Token — In Graph API Explorer, select your app, get a User Access Token with scopes: instagram_basic, instagram_content_publish, pages_show_list, pages_read_engagement.
5. Instagram User ID — After the above is set up, the system auto-discovers your IG User ID when you add the account. If it's blank, you can find it:

Finding your Instagram User ID:

• In the Access Token Debugger, enter your token and look for instagram_business_account in the metadata.
• Use GET https://graph.facebook.com/v19.0/me/accounts?fields=instagram_business_account&access_token=YOUR_TOKEN in your browser or curl.
• Or just paste the numeric ID in the Instagram User ID field below if you already know it.