Technical SEO is important because it essentially ensures that your website is easy to navigate and is free of any technical issues that prevent it from being understood and ranked by search engines. You should implement technical SEO to attract organic traffic and turn that traffic into customers.
Robots.txt
* Robots.txt file is insure google spider  which file is allowed to Crowell and which is not.
* So it is a security issue for your website. Because your admin panel is very important to take  security.
Xml Sitemap
* Xml sitemap is like a map of your website. When google spider come to your website to index your post and page, In this case spider needs a map to  Crowell your website. Without map google dose not make a good Crowell.

Canonical tag :
* Colonial tag is very important to protect your website from copyright calme. It influence google spider to don’t take any post or page in seconds time.
So it is important to rank your page.
 
404 error
* when any page or post of your website had deleted. And people doesn't take any content to follow your link. In this case you have handle this by make 301 redirection . Otherwise google take this as a bad think. And it’s make ranking difficulty for your website.

Google search console

Google Search Console is a free service offered by Google that helps you monitor, maintain, and troubleshoot your site's presence in Google Search results. You don't have to sign up for Search Console to be included in Google Search results, but Search Console helps you understand and improve how Google sees your site.

Google analytics
Google Analytics allows you to track and measure many important metrics that will help you to grow your business. You can track and monitor the effectiveness of your online marketing strategies, website and social media content, user experience, and mobile-friendliness.

All of these things are very very important for rank your page in first page of google.
 I am a seo expert so all of these setup I will be your best choice.