Hi Phoebe,
Please use the below github link for Auto login functionality in mendix.
https://github.com/tieniber/AutoLogin
Thanks,
Ragul.
Dear Phoebe Tan, It seems like there is no autologin module in the marketplace. However, on github, I have found an autologin module for mendix which was created by someone else. I haven't tried it but maybe it helps you.
https://github.com/rcha103/-EOL-MxAutoLogin
Kind Regards, Yusuf KAZAN