How do I combine the last three boxes (name, phone and email) into the same box?

Do you want to show all three fields on the same page?

If so, you can use the Multi-Line Question field. The Name field is not one of the field options in the Multi-Line Question field, so you will have to use Text Box fields, one form the First and one for the Last Name.

Card Forms: How to Utilize the Multiline Question

Here is a demo form - https://form.jotform.com/82911014056953

Feel free to test it and clone it.