Deploy an application using dll files to IIS on a VM

I hope I am posting this in the correct forum, but to me at least, it seemed that the focus was more on deployment.

I am currently stuck after having successfully refactored an application by extracting certain responsibilities into
class libraries (language: C#, .NET 4.8).

The application is hooked up to Azure CI builds using Azure DevOps, deploying the application to an IIS on a VM. Pipelines are triggered upon commit.

The pipeline looks roughly like this:

• NuGet restore

• Build Solution

• Test Assemblies (Visual Studio Tests)

• Publish symbols path

• Publish Artifact

The .dll files are located in a dedicated folder within the application.
I am referencing the .dll files in the application and have already changed their property Copy to Output Directory to Copy if newer.
When building the application on my local machine, the required custom .dll files are being copied to the bin folder as expected.
However, when analysing the deployment logs, I noticed that the custom .dll files are not being updated / copied.

How can I make sure that the custom .dll files are deployed properly (same as the standard .ddl files)?

It seems that there is no other way than creating NuGet packages from those .dll files required for the build, as this post on SO points out.

StackExchange DevOps Q#14410, answer score: 1