Last year, Ahrefs removed it’s limited free plan including the SEO extensions.
But now they have introduced a new free plan again, Ahrefs Webmaster Tools.
As Ahrefs is pretty costly for most of us, now you can add your sites and check the site explorer and site audit tool for free as long as you verify your website (via GSC, DNS, record, or HTML entry).
Note that if you verify your site via GSC, they will anonymously take data to improve their estimates. They’re doing this probably because Jumpshot isn’t available now, but the GSC data from websites should overall help improve the keyword and site data. So it’s a win-win for everyone!