If you migrate from devon-docgen to devonfw-docgen (5.0.0+), you have to choose your target output format to generate via the artifactId of the docgen parent in your pom.xml. So instead of the artifactId which was devon-docgen you now have to use devonfw-docgen-pdf (or devonfw-docgen-html in case you generate HTML output).
Also you need to know that the property docgen.wiki.page has been renamed to docgen.asciidoc.page.