Newbie here. Need help downloading an article with a PMID.

I have searched for the DOI everywhere, and it doesn’t exist. But scihub isn’t showing any result with the PMID. The article in question is this:

[https://pubmed.ncbi.nlm.nih.gov/21009851/](https://pubmed.ncbi.nlm.nih.gov/21009851/)

Thanks in advance for the help.