Here is how you can access you Facebook Ad Account ID, through your Facebook Business Account.
There are two ways to find your Facebook Ad Account ID
1: Within the Account Dropdown Menu in Ads Manager
- Go to Ads Manager
- Your ad account ID number is shown above the search and filter bar, in the account dropdown menu.
2: In you Browser's address bar in Ads Manager
- Go to Ads Manager
- Find the number in your browser's address bar. If you have trouble locating your ad account in the address bar, look for act= in the URL.
You can find more information about Facebook Ad Account ID through here.