Using AppAuth for Twitter, Paypal & Linkedin Sign in

Question

I am unable to use any of these successfully.

Twitter Config

 {
  "client_id": "",
  "redirect_uri": "https://callback.com/landing/twitter/login",
  "authorization_scope": "read",
  "discovery_uri": "",
  "authorization_endpoint_uri": "https://api.twitter.com/oauth/authorize",
  "token_endpoint_uri": "https://api.twitter.com/oauth/token",
  "registration_endpoint_uri": "",
  "user_info_endpoint_uri": "https://api.twitter.com/1.1/account/verify_credentials.json",
  "https_required": true
}

The error for twitter is

Paypal Config

{
  "client_id": "",
  "redirect_uri": "https://callback.com/landing/paypal/login",
  "authorization_scope": "openid email phone address profile",
  "discovery_uri": "",
  "authorization_endpoint_uri": "https://www.paypal.com/signin/authorize",
  "token_endpoint_uri": "https://api.paypal.com/v1/oauth2/token",
  "registration_endpoint_uri": "",
  "user_info_endpoint_uri": "https://api.paypal.com/v1/oauth2/token/userinfo",
  "https_required": true
}

Paypal I am able to open the page and signin. I get failure at authorization code exchange.

Linkedin Config

{
  "client_id": "",
  "redirect_uri": "https://callback.com/landing/linkedin/login",
  "authorization_scope": "r_basicprofile r_emailaddress rw_company_admin w_share",
  "discovery_uri": "",
  "authorization_endpoint_uri": "https://www.linkedin.com/oauth/v2/authorization",
  "token_endpoint_uri": "https://www.linkedin.com/oauth/v2/accessToken",
  "registration_endpoint_uri": "",
  "user_info_endpoint_uri": "https://api.linkedin.com/v2/me",
  "https_required": true
}

The signin proceeds for linkedin and the redirect page is opened, with the code in the url. The flow stops there. So would I need to capture this on the server? Or AppAuth would handle it? Testing on Android Oreo.

Any suggestions?