ATContentTypes cannot be used on Python 3. You must first go to Plone 5.2 on Python 2.7, start the site, run the upgrades at @@plone-upgrade, then migrate the ATContentTypes content (based on Archetypes) to plone.app.contenttypes (based on dexterity). See the plone.app.contenttypes documentation, especially the migration part.
Also, the migration docs from Plone 4.x to 5.0 point to a video of a talk “How to upgrade sites to Plone 5” and slides. That could be helpful.
About copy/paste: if the content of your site is only a few pages, then it is probably much easier to start with a fresh and standard Plone 5.2 Python 3 site, and recreate the content manually.
Also, see this current thread about migrating an even older Plone, with alternatives for the in-place migration from above: Migrating ancient Plone 2.1 -> 5.2. What approach would you recommend?