Activation code not accepted

Hi everyone
Recently I installed S4L Light, but I couldn't activate it successfully. I provided a valid email address and clicked 'Request Code'. When I enter the activation code which sent to my email, it said 'Activation code not accepted'.
I kept the same dialog open in the whole process.
I can't figure out what the problem is. Appreciate it if you could help me with the problem.

Dear all,

we have released a new online simulation platform called S4L lite. You can register via this link

https://zmt.swiss/support/support/s4l-lite/

and you can login and start using it without any installation.