Even without "upgrading" to AEM Forms Designer, you can get a fairly up to date version by applying the latest quick fixes for Designer 11. The QF9 will bring you pretty close to AEM Forms Designer 6.1. See https://experienceleaguecommunities.adobe.com/t5/adobe-livecycle-questions/quick-fix-1101-002...

PDF.JS (the pdf renderer for FireFox and other browsers) has added basic XFA support. Learn more here: https://github.com/mozilla/pdf.js/releases/tag/v2.8.335 

If you are using Dynamic XFA strictly to merge content (i.e. XML that is provided from the server), you can flatten the PDF before it gets to the end user. LiveCycle (AEM) Server and iText XFA Worker can do this.

The form you are attempting to open is a dynamic XFA form. These forms can only be opened in an XFA aware reader, which basically means Adobe Acrobat. You must download it and open it with acrobat/reader in order to view it.

Well with Acrobat XI they replaced LiveCycle with FormsCentral, which used LiveCycle internally but ultimately produced AcroForms. After XI, they removed a form generation product altogether in Acrobat, suggesting SMBs use a third party product, or look at AEM Forms. AFAIK, there are no drop in repl...

I have a theory that Adobe is actively discouraging the sales of this product because it perpetuates the use of the PDF 2.0 non compliant XFA format (You can technically make a standard PDF with LiveCycle / AEM Forms, but not easily). However, they are willing to keep it going for those who bought i...

The dyn is a vendor extension and only certain XSLT engines will support it. I'm not sure what engine the online transformation tool is using.

Try dyn:evaluate()xsl:stylesheet version="1.0"  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"   xmlns:dyn="http://exslt.org/dynamic"  extension-element-prefixes="dyn">  <xsl:param name="path"/>  <xsl:output method="text"/>  <xsl:template match="/">  <xsl:value-of select="dyn:evaluate($path)"/>  <...

Yes, you can embed an XSLT into your XDP and have it run before the data is merged in the form. Keep in mind that Acrobat only supports XSLT 1.0, using a processor called Ginger Alliance.

You can use the approach you mentioned earlier, or consider AEM Forms, or a  third party "flattener" tool that will convert the XFA form to a static document of record.