From simumatik.com you can log-in to your account or even sign-in to create a new one by clicking the Login button. Once logged-in, click on the Account dropdown and then picking 'Go to app'. Otherwise, you can direcly access app.simumatik.com and log-in there.
Then, the login page will appear and you will be able enter your email address and password to access the app.
If you do not have an existing account, follow the instruction on Manual>Accounts>Management to create one.