PHP coding for Form - Fixing some small issues

We have a form that is built on php. It works inside a CMS, but the developer isn't required to work with the CMS.

The form we have works perfect in PHP 7.4, but we've now started using PHP 8.2 and the code no longer works well. It's hard for us to know where the problem is so we intend to work with a developer to tackle each problem individually and see if that fixes it, before moving on to the next one.

First problem, we believe that we are having an issue with the div's on the form.

The form is located here on our test site

https://vpas.uk/posts

The form has two pages to complete before it sends the information to a third party. As you may see, the input fields are not aligned and there are some errors. We even have one field "consent" that isn't appearing at all on the second page and that is preventing customers from submitting the form.

Ideally if we can find a good developer, we would like to work with them to fix this form, then go on to rebuilding the form to include making it more user friendly and auto completing addresses etc.

We will provide FTP details, so the user an make changes to the live test site if they wish.