Implementation of okta in web form application

We have existing web form application. This application is linked to another end point for example, which contains buttons to link with application. On click, it calls default.aspx page with query string . For example:
I have to call okta login page before loading default.aspx page and authenticate user. Also querystring parameter should be available after successfully login.
I am not sure what to be use to authenticate it with OKTA. I tried with oidc flow but unable to set querystring parameters in redirect uri. I want to only authenticate using userid and password using okta login page and redirect to page with query string.
Thank you in advance for any help.

did you get answer for your question?
because i also face same issue.