Starterkit Installation not working - followed every step from the tutorial

I did everything in the terminal exactly as shown in the tutorial. I the copied the adress in my web browser, and it opened this:

"this page is currently offline. We are very sorry for the inconvenience and will fix it as soon as possible.

Advice for developers and administrators:
Change the PHP version to one supported by your version of Kirby"

What to do now? Is this because i did something wrong? I would really appreciate the help, im really stuck here guys… thanks.

Kirby requires PHP 7.4+, so your PHP version is not compatible.

I assume you are using PHP’s built-in server? check with php -v which PHP version you actually have.