I was running this project every day but today it is not working.
"Target framework 'net5.0' is out of support and will not receive security updates in the future. Please see: .NET and .NET Core official support policy for more information about the support policy."
This is not related to Radzen - most probably you cannot run your project using dotnet run as well. The important error is duplicate PackageReference - check your csproj.
I can run the project with visual studio.
Can you run it using
dotnet run? This is what Radzen is using.