SEO isn’t an exact science, it’s a combination of theories and best practices, with years of experience. What might be working for one website, might not work for another.
If the SEO Checker has given your website a good overall score but you’re still having difficulty ranking, then it’s likely you need to dig deeper for the reason why.
The SEO Checker mainly looks for common onsite SEO issues, however, even the most well optimised website still won’t rank without traffic coming to the site, or a decent CTR from the SERP’s.
There are a lot of factors that might be holding you back, such as a poor backlink profile, a penalty from Google, duplicate content, over or under optimisation of anchor text, or poor CTA’s.
If you’ve received a good SEO Checker score but your rankings or campaign results are poor, it’s likely an SEO expert could help to resolve your issue.