How to install theme on Opencart 3?

Question

opencart

When installing the theme on Opencart 3. I get an HTTP ERROR 500 error.

I do this:
1. Download the archive with folders (admin, catalog, image, system).
2. I throw them into the root of the site with the replacement of existing ones.
3. Next, at the stage, you need to update the modifiers, but the admin panel no longer enters - HTTP ERROR 500.

What am I doing wrong?
This happens with any topic.