In order to enable Facebook share and Facebook log-in on your website, you need to fill up the “Facebook App ID” in the “G. My Store -> 3. Store Setting->Social Media -> Facebook” tab below.
Facebook Share at product page
Log in with Facebook
How to get Facebook App ID?
Step 1: Log in to Facebook and then navigate to developers.facebook.com. If you yet sign in to your Facebook account, select login on the top right to sign in to your account.
Step 2: Select “My Apps” on the top right, then select “+ Create App” from the dropdown list.

Step 3: A window will pop-up and ask you for your Display Name (The name displayed to users) and your contact e-mail address. After entering the content, click on “Create App ID”.

Step 4: Add the “Facebook Login” product to your app by click on “Set Up”.

Select the “Web” as the platform for this app.

Update your “Site URL” and click on “Save” button.

Step 5: Add in your APP privacy policy URL and choose a category that is suitable for your business. Then, click on the “Save Changes” button.

Step 6: Go to “Facebook Login -> Settings” to fill up the “OAuth Redirect URLs” as below:
a. your domain/ website URL
b. your domain / website URL+ /externallogon/signin-facebook
Step 7: Live your app by enabling your APP status and now you are done.
Step 8: Grab your App ID and App Secret from the screen to update it in the merchant dashboard.