The Additional Downloads dropdown on the Windows Server Insider Preview download page is being temporarily removed. It contained an older preview of Windows Admin Center. Windows Admin Center 1910 is the latest GA update release and we recommend customers upgrade if they have not already done so. In the short term, we are focusing on quality updates and so we are pausing feature preview releases on the Insider program. We will resume feature preview releases of Windows Admin Center again in the future. We also encourage you to visit the Windows Admin Center space on the Microsoft Tech Communities forum to collaborate, share and learn from experts.