SSO Auth0 between Salesforce and Angular

The project that I’m working on requires user to login from Salesforce lightening app and redirect it to external page Angular which bypasses the login page of angular and enter to dashboard which is nothing but SSO.

Currently Salesforce app is integrated with Auth0 application and user management is taken care by Auth0. If user is not logged in Salesforce App, he/she should be redirect back to salesforce login page.

Currently when I keep my logic in authGaurd.ts, I want to retain my key in the URL that I get from Salesforce App which cannot be captured.

Kindly help me in this scenario.