Please follow the steps below:

Facebook

First off, you need to have your Page ID or Name.
e.g. facebook.com/Bdaia
or facebook.com/pages/Bdaia/1550989220123

You can notice that the page name is: Bdaia
The Page ID: 1550989220123

The second step is to Register a new app by heading to Facebook Developers page and choose “Add a new App” under “My Apps”.

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Click Website

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Click “Skip and Create App ID”

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Enter Display Name, Namespace and choose a category for the App.

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Complete the security check, then click Show button to display the App Secret key.

After that, please head to this page and scroll down to point number 12. Enter your App ID and App Secret to get your access token.

Once you’ve your token, go to Widgets > Social Counter widget and enter your Facebook Page Name/ID and the access token to get your counter works.

Google +

You have to get your Google+ page or profile ID. If Your page Link is like http://plus.google.com/+psdtuts/ the ID will be +psdtuts , if your page Link is like http://plus.google.com/106192958286631454676 the ID will be 106192958286631454676

1. Create a project/app: https://console.developers.google.com/project

2. Inside your project go to APIs & auth > APIs and turn on the Google+ API

3. Go to APIs & auth > APIs > Credentials > Public API access and click the CREATE A NEW KEY button.

4. Select the Browser key option and click on the CREATE button.

After that, copy your API key and paste it inside API Key field in Google+ counter and enter your Page ID/Name.

Instagram

1. Make sure that you’re logged in Instagram.com website, then visit: http://instagram.com/developer

2. Click “Manage Clients” link.

NOTE: If this is the first time you are adding an app or plugin, Instagram will ask you a few questions. You can complete the process and click “Sign Up”, and then click “Manage Clients” again.

*Example*
Your website: Enter your website url
Phone number: Enter your phone number
What do you want to build with the API? A plugin for my WordPress website.

3. Click “Manage Clients” again, and register your WordPress site by click the “Register a New Client” button.

4. Fill in the “Register new OAuth Client” form with the following information and click “Register”:

Application name: Enter the name of your WordPress website
Description: Instagram App for my site
Website: Enter your website url
OAuth redirect_url : Your-Blog-URL/wp-admin/

(Change Your-Blog-URL with your WordPress Blog URL)

4. Copy the Client ID and Client Secret.

5. Go to http://instagram.pixelunion.net/ to get your Access Token Key.

6. Copy your Access Token Key and go to your Dashboard > Appearance > Widgets > Social Counter and enter your Instagram username and the Access token key.

Youtube:

1. Create a project/app in https://console.developers.google.com/project

2. Inside your project go to APIs & auth > APIs and turn on the YouTube Data API

3. Go to APIs & auth > APIs > Credentials > Public API access and click the CREATE A NEW KEY button.

4. Select the Browser key option and click the CREATE button

5. After you’re done, Copy your API key and paste it in Youtube API field in Widgets > Social Counter widget > Youtube box and choose User or Channel ID.