Migrating from Drupal

I have been using the scripts in this article to try to move posts and pages to a wordpress site from a drupal site. https://blondish.net/how-to-convert-drupal-to-wordpress/

The posts and pages are moved over fine, but clicking on an individual post results in a 404 error. I can resolve this issue any particular post by going into edit it and clicking “save” on the permalink settings.

Two questions:
Does anyone know a better (free) method to migrate my content across?
Is there a fix for these scripts that will make the permalinks work without having to fix each and every post manually?

Thanks so much for any help!