When users start an app, they will have to allow notifications from the app. The question about notifications should pop up automatically on the screen. Participants will also need to create a new account. The login information will be stored securely on the Samply server (which is the server of the University of Konstanz in Germany) and used only for authentication of users.
After logging in, participants can either scan the QR code of your study (available on your study page) or find your study in the list of public studies. When participants open your study in the app, they will see the description and welcoming text. By clicking on the "Join the study" button, participants will allow to receive notifications from you. They can now close the application.
You as a researcher will not have access to email addresses of participants. If you wish to have participants' email addresses, you are free to collect them together with other information via your online studies. Instead, Samply will share with you a unique id of each participant (in the form xxxxxx), which you can include as a query parameter in the link of your study. More information about that is in "Notifications".