Why has Google not indexed directory backlinks?

I'm new to SEO and I know a big part of SEO is backlink building. I'm having troubles with getting directory submission backlinks indexed. I understand that most are generally either low quality or spammy and should be avoided.

Is there a ways to get a page indexed by Google (if I don't actually own the page, so Google Search Console is not an option? Will pinging or sharing the backlink across social media platforms get the page indexed by Google?

thanks!