Obtaining informed consent ensures the users' autonomy and privacy, and that the users are aware of potential risks and benefits of your HCI study. To get an informed consent form for your participants you can use this generator. This informed consent is not suitable for vulnerable groups (children, disabled, prisoners) or when any harm can occur (medical studies).
When you collect any personal information in the EU, the GDPR applies and sets strict rules for processing the data and is based on consent. That consent should be freely given, specific, informed and unambiguous by way of a request presented in clear and plain language.
Consent should be given by an affirmative act, such as checking a box online or signing the form. Please reach out to your supervisor in case of any requests.