Pressing the Enter key submits the form

Also, when I enter a number in the "how many booklets" field and press enter, it submits the document whether it is finished or not. I do not want the how many booklets to submit when I press enter, but rather when I press the submit button.

Forms were designed that way (regardless if it's built in Jotform or not). This is something referred to as Implicit Submission as described in HTML5 specifications. This behavior doesn't just apply to your How many booklets field, it applies to the entire form regardless of what field is used (e.g. regular textboxes, one of our Quick Fields, etc.)

This is important to accessibility, assistive technologies and impaired users that cannot use a mouse at all. There are pages on the Web that are only usable if there is a way to implicitly submit forms, so user agents (browsers) are strongly encouraged to support this.

If you really want to suppress this default behavior of forms, the only way around it with JotForm is to get your form's entire source code and use Javascript to prevent the Enter key from submitting the form.

I found a really good read about this topic on this post in case you're interested to know why it was designed that way. At the latter part of that post will be alternatives on suppressing it (especially the Explicit Prevention part where they gave an example JS code snippet to prevent it).