Can't create Virtual Device (AVD) in Xamarin Studio

Question

I downloaded everything from the Android SDK (literally everything), and the version is 24.xx. I want to make a Nexus 5 (4,97") AVD, but it requires API Level 19. And when I try to install Xamarin again, it says that I haven't installed Xamarin v3.9.236. When I try to install, it gives me 3 errors:

**Installation of 'Xamarin' failed with more than one exception (attempt 3)**

Errors while installing items. Exception type: System.AggregateException Installation of archive 'C:\\Users\\Robi\\AppData\\Local\\Temp\\Xamarin\\downloads\\Xamarin.VisualStudio_3.9.236.msi' failed with exception.

Exception type: Xamarin.Web.Installer.InstallException Full stack trace: at Xamarin.Web.Installer.Installer.InstallationArchiveHandler.Install(String path, Boolean needsPrivileges) at System.Dynamic.UpdateDelegates.UpdateAndExecuteVoid3[T0,T1,T2](CallSite site, T0 arg0, T1 arg1, T2 arg2) at Xamarin.Web.Installer.Installer.BaseSoftwareItem.InstallDownloadedItem(String url, InstallationArchiveHandler handler, DownloadServiceWorkItem download) at Xamarin.Web.Installer.Installer.BaseSoftwareItem.Install(UInt32 tryNumber) at Xamarin.Web.Installer.Installer.XamarinVSSoftwareItem.Install(UInt32 tryNumber) at WindowsInstaller.ProgressPage.InstallationWorker()

Installation of archive 'C:\\Users\\Robi\\AppData\\Local\\Temp\\Xamarin\\downloads\\Xamarin.VisualStudio_3.9.236.msi' failed with exception. Exception type: Xamarin.Web.Installer.InstallException Full stack trace: at Xamarin.Web.Installer.Installer.InstallationArchiveHandler.Install(String path, Boolean needsPrivileges) at Xamarin.Web.Installer.Installer.BaseSoftwareItem.InstallDownloadedItem(String url, InstallationArchiveHandler handler, DownloadServiceWorkItem download) at Xamarin.Web.Installer.Installer.BaseSoftwareItem.Install(UInt32 tryNumber) at Xamarin.Web.Installer.Installer.XamarinVSSoftwareItem.Install(UInt32 tryNumber) at WindowsInstaller.ProgressPage.InstallationWorker()

Installation of archive 'C:\\Users\\Robi\\AppData\\Local\\Temp\\Xamarin\\downloads\\Xamarin.VisualStudio_3.9.236.msi' failed with exception. Exception type: Xamarin.Web.Installer.InstallException Full stack trace: at Xamarin.Web.Installer.Installer.InstallationArchiveHandler.Install(String path, Boolean needsPrivileges) at Xamarin.Web.Installer.Installer.BaseSoftwareItem.InstallDownloadedItem(String url, InstallationArchiveHandler handler, DownloadServiceWorkItem download) at Xamarin.Web.Installer.Installer.BaseSoftwareItem.Install(UInt32 tryNumber) at Xamarin.Web.Installer.Installer.XamarinVSSoftwareItem.Install(UInt32 tryNumber) at WindowsInstaller.ProgressPage.InstallationWorker()