How do I install portal app?

Could you please provide me with a step-by-step guide on how to install the portal app? I'm not very familiar with the process and would appreciate it if you could walk me through it. Are there any specific requirements that I need to meet before installing the app, such as a certain operating system or device? Additionally, is there a fee associated with installing the portal app, or is it free to download and use? Thank you for your assistance.