Check that Internet Explorer Enhanced Security is switched off otherwise the installation may fail or stall.
Install both prerequisites : Microsoft .NET Core 3.1.13 and Microsoft .NET Core 3.1.25 - Windows Server Hosting. The download link is: https://dotnet.microsoft.com/download/dotnet/3.1.
Otherwise you may see 'Method not found' during install OR the config settings may not have been changed in index.htm and web.config
Use the later version of SetUpWebSite.ps1 which allows installation even if Office is not installed on the server. You may get 'Method not found' during install.