the weird thing is that I'm not seeing anything wrong with your site. It has...
- the right amount and quality of content
- lots of RDs and backlinks
- good on-page and technical SEO
- natural growth of traffic and organic keywords (albeit very little of them)
- good anchor texts
And this particular URL is also indexed in google, so I genuinely see nothing wrong with the site, which really puzzles me...
The only potential issues that might exist, are:
a) you're not ranking in top 10 for any keyword and - for whatever reason - google might take this into account. I'm not saying that this is a valid reason for your non-ranking, but in the absence of more concrete evidence I had to say it lol ... So anyway, try to get some top 10 rankings (even if for ultra long and meaningless keywords) and see if this improves your overall rankings. Given that your site is good overall I think you can easily rank 10-20 pages of 500-600 words long content for 6+ long keywords within a few short weeks.
b) the content of this page is split into tabs and - again, for whatever reasons - google might think that this is not cool (although, to be honest, I've never heard of this being an issue and if you're ranking other pages with the same content layout then it's definitely not an issue)
c) you're linking to your own page from the same page... Not sure whether this is reason for not ranking, but it's definitely not normal and you should remove those self-links (I don't know how else to call them, sorry)
And speaking of internal linking, I didn't check whether you have any internal links pointing to this specific page, but if you don't have any, get some! Orphaned pages (pages that have no traffic and no links pointing to them do tend to lose their rankings)
Something else that I recommend that you do is analyze the backlinks of your competitors to see if you can get the same (preferably strong) links that your competition has. I didn't check your site in depth, so I don't know what links you, or your competition has, but this is something that you should do. So, if your links are not very good get some good ones (good links = links from quality sites that have traffic, or links that have decent PA / UR and even organic / referral traffic whenever possible)
If you do all of these but still don't rank pay someone to do a more in-depth analysis than I did, because I honestly can't figure out what's wrong...
https://www.blackhatworld.com/forums/hire-a-freelancer.76/
PS: try not to make your sites and keywords public, it's bad omen
