Hi Ben,
Thank you for posting your question here and we are happy to help you regarding hosting your ASP .Net application.
Based on the error message you have mentioned above, I believe you are using Dot CORE version. And to deploy any code application, you have to install the "Hosting bundle" provided by Microsoft. This will take care of all required Installable for running your application.
Please refer following link for additional information and kindly feel free to get back for any additional queries.
Install the .NET Core Hosting Bundle on your machine or IIS server where you are trying to host. The bundle installs the .NET Core Runtime, .NET Core Library, and the ASP.NET Core Module. The module allows ASP.NET Core apps to run behind IIS.
https://dotnet.microsoft.com/permalink/dotnetcore-current-windows-runtime-bundle-installer
Run the installer on the IIS server.
Restart the server or execute net stop was /y followed by net start w3svc in a command shell.
Besides, here's a document about deploying .NET Core application.
.NET Core application deployment - https://learn.microsoft.com/en-us/dotnet/core/deploying/
Hope it could be helpful.
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