Link and Learn Taxes is maintained by the IRS. You can access Link and Learn Taxes on the IRS website by navigating to https://apps.irs.gov/app/vita/
Additionally, there is the certification website, VITA/TCE Central, that is also referred to as "Link and Learn Taxes" on occasion. This website is also maintained by the IRS and is supported by a separate team. This website can be accessed by navigating to https://linklearntaxescertification.com/