Hello,
When you access to WAP, the user has an a new cookie called "EdgeAccessCookie", so as far as I know you can't use your internal cookie.
More details on :
http://blog.lerun.info/2016/10/08/wap-adfs-the-persistent-cookie-conundrum/
https://tristanwatkins.com/coordinating-adfs-2012-r2-token-lifetime-logon-prompt-enforce-revocation-session-duration-public-network/