Want SSO working with the php apis , unable to find any particular solution

I am using php apis for login and it is working fine with Auth0, But there are another application i want to do automatic signing in those applications , but it is not working .
I have tried Universal login page and it is working fine , it login me to another application automatically when i login to any of the one.
But i donot want to use the universal login page , i want to use the api with my website forms and login and signup is working fine with api , but when i go to another application it never work .
This is the flow i am using

  1. Login to my php app( wordpress ) with api
  2. open another app and it lands me to universal login page , but now it is not login me automatically.

I want to login to another appp automatically , can you please tell me where i am doing wrong or missing something .