Restart Zotero and try again. It could also be a problem with your internet connection.
That link is just loading https://www.zotero.org/styles in a window. If you have the Zotero Connector installed in your browser, you can install pages just by clicking on them on that page.
Upgrade Storage
That link is just loading https://www.zotero.org/styles in a window. If you have the Zotero Connector installed in your browser, you can install pages just by clicking on them on that page.