First, a distinction worth keeping in mind: crawling and indexing aren't ranking. You can have thousands of pages indexed and still not appear in front of users. Ranking is up to search engines, but you can help bots discover more of your pages.

Check that it really isn't indexed

Search with operators like site:, allinurl:, and intitle: before assuming there's a problem.

Then work through these steps

• Use the URL Inspection tool in Google Search Console: run Test Live URL, then Request Indexing.
• Get a natural, unlinked mention or a direct link pointing to your index page.
• Run an advertising campaign.
• Create a page on an external domain describing your white-label business, link to your index page, then repeat the steps above.
• Look into the Indexing API, keeping in mind it may not work for explicit content.
• Consider the Stripcash API for Aggregators and build a satellite site for your white-label.
• Develop a link-building strategy.

One more thing

The larger and more relevant your existing organic traffic sources, the easier it is to send visitors to a new domain. Building up additional traffic sources pays off when you launch your next white-label.

References: https://ahrefs.com/blog/google-advanced-search-operators/https://developers.google.com/search/docs/crawling-indexing/ask-google-to-recrawl