WordPress is written in PHP, so if you want to use it as the basis of your site, then most likely you'd want to use PHP to modify it to your specific needs -- or even see if there is is a WordPress plug-in you could use?
One advantage of a PHP-based approach is that virtually any web-hosting provider you use will support it out of the box. That's not to say you can't get reasonable hosting for any of the others -- just that you need to be a bit more careful about choosing the right provider and package to get what you need in those cases.
Depending on what you really need to accomplish, it may be overkill. If it's just adding a div to the page that includes some member data and a registration/login capability, WordPress or any other CMS may be overkill. Maybe a few dozen lines of PHP along with the HTML/CSS markup is all you need, along with a registration/login page with perhaps a bit more PHP? 🤷♂️
Also, WordPress is not the only CMS choice. Here's one random article I found comparing it with Drupal for a non-profit/charity site: https://www.johnhaydon.com/nonprofit-website-drupal-wordpress/