Really neat solution. I'm a noob and also currently working on this project. This is my first feedback so take my advice with a little bit of caution.
I would really recommend to use labels in your form. Labels help with accessibility and semantics and is also a must for every form (at least according to this decent article https://austingil.com/how-to-build-html-forms-right-semantics/). Keep in mind that if you will choose to add labels, I think that your form will look different. To hide labels you can use this little trick https://austingil.com/how-to-build-html-forms-right-accessibility/#:~:text=The%20%E2%80%9Cvisually%2Dhidden%E2%80%9D%20Utility%20Class
In your "free-trial" div I would suggest to use <strong> tag instead of styled span tag. <strong> tag is also a part of semantic HTML code (https://medium.com/before-semicolon/10-html-semantic-tags-and-when-to-use-them-5ae7d7d0b0f2)