You need to delete or comment on these lines which are not needed now. or you can add a null check on them. Since they don't exist on the form now so better to delete their reference in the script. if(field_Xpath){   }

try this:<span style="color:Red;">Hello ${firstName} ${lastName}</span>  

Use the below script code in the initialize event:   this.validate.nullTest = (this.rawValue) ? "" : "error";

Yes, calculations in other fields can cause issues.

The script is working now, you can modify the logic as per your requirement

Please use the below-modified script, which worked for me.   if (tblCourse.row8.reimbApproved.rawValue < tblReimbRcvd.row3.cost2Dec.rawValue){this.rawValue = tblCourse.row8.reimbApproved.rawValue;}else if (tblCourse.row9.proRatedApproved.rawValue < tblReimbRcvd.row3.cost2Dec.rawValue){this.rawValue ...

Please see the link and attached image for confirmation.   https://experienceleague.adobe.com/docs/experience-manager-65/forms/install-aem-forms/jee-installation/installing-configuring-designer.html?lang=en  

Please check the somExpression of fields if they are resolving properly. This may be the reason or you can share your form @ (vkatoch07@gmail.com), I'll have a look.

Your Adobe ID should be linked with your Adobe Experience Cloud solution accounts to download the installer. When you bought it, Adobe must have sent you an email or some link to download it.

XDP files are specifically designed for Adobe's form creation and merging them with the XML to create the PDF document can be done with the AEM services either directly or using their API programmatically.