You will need to use a microflow to handle this. Kindly go through this article it explains a lot about login and especially auto-login and handling the subsequent steps:
https://medium.com/mendix/mendix-autologin-with-deeplink-1c8fa92873a8
https://academy.mendix.com/link/path/82/Crash-Course
Step 8.7.1 gives details about creating accounts, this will also come handy