Cannot see Test Cases in Visual Studio or associate a test case for automation

We're using Azure DevOps to undertake release headless testing of a capability build and maintained in GitLab. To overcome a requirement to stage in DevOps and use Devops ONLY for Test Plan management and automation in testing, we've added a purposed Linux agent, which enables us to successfully execute a pipeline to current bash script the code updates, clone the project repo and undertake a simple headless API test in the bash script. I'd like to move this to a test case.

I've installed Visual Studio BOTH community and Enterprise and attached to our DevOps. I can see work items but cannot see any test plans in Test Explorer - I've attempted to follow the numerous articles to address this unsuccessfully. Would value consult from anyone that has a achieved this and perhaps a simple example?

The ability to see a simple test case and associate it for automation to execute a series of API commands as part of a test plan.