I’m not familiar with either of those plugins, and I don’t know what backup formats they produce. If the old installation you’re trying to restore is still up and running, I would highly recommend to just follow the instruction from the article and migrate the website as-is without using any plugins or partial migrations.
Beyond that, the steps look good for the most part.
For step 2, you may need to copy everything to the htdocs folder directly, rather than just the wp-content stuff. That depends on whether these backups include the WordPress installation itself as well. If not, you will also need to upload a copy of WordPress to your account first and do the restoration of the content afterwards.
As for step 5, I think that should be to update the wp-config file to have the database credentials of your new account, rather than changing the credentials of the database itself to match those of the old account. With most hosting services, database names and usernames are prefixed with your account username, so they are not fully customizable and cannot be changed to match exactly with your previous host.