Where do I find db_config.php?

Hello everyone, I hope that you are all well.
Environment - latest version of WP
Multisite sub-folders installation, hosted test environment set up as add-on domain. Use cPanel.

Followed the instruction as per thread https://premium.wpmudev.org/project/multi-db/#usage, created 256 dbs using https://premium.wpmudev.org/db-tools/db_sql.php (very useful tool by the way, thank you). Pasted the results into myphpAdmin and clicked GO, then got a message: "#1 row affected")
Can not find db_config.php in the wp-content folder.
Please advise how to continue installation or how to re-install in case this is necessary. Please advise on what to do. Thank you for your support.