Question on templates

The folder is just where Ocean WP’s developers chose to store its templates. It’s not something for you to do anything with. If you want to create your own custom template you need to create a Child Theme and create the template there. If you create or modify files in a theme they will be erased if/when the theme is updated. Creating a Child Theme avoids this issue.

Regarding the error, putting a file into a theme wouldn’t throw an error on its own. You likely had a syntax error in the code of the template.