I usually scrape my followers number with the function importXml.
For followers number : =CNUM(REGEXEXTRACT(IMPORTXML(YOUR INSTA URL;"//meta[@name=‘description’]/@content");"(.{1,})(?: Followers)"))
The number of post should be easy too with this, but I don’t know how to scrape the number of like and comment from the last 20 post, I think you can with ImportXml but you have to try.