Is it still important to create an external link

The MOST important factor for SEO is high quality content, so do that first.

Then do other on-page SEO factors, such as good internal linking, image Alt text, HTTPS, and "about" "contact" "privacy policy" and "terms" pages etc.

Then you can start doing off-page SEO such as creating back-links. The most important thing about back-links, is to ONLY create links from sites with DA of 20+, and pages which have content related to yours, else you are doing your SEO more harm than good. You can create back-links by blog commenting, guest-posting, forum signature links etc.

You also need plenty of social-media links and signals (Likes, Shares etc.). While these don't affect your rank directly, they show Google that people like content, and without that, you won't rank well.

Hope this helps you understand how to create external links which actually HELP your ranking (most people do it wrong!).

Chris