Do deploy this stack first the dotnet solution needs to be build , you can do that running
dotnet build ./LayersTesting/LayersTesting.sln--configuration RELEASE -p:PackageLambdas="true"
After that you can run a build and deploy of the infrastructure goind to the infra directory and :
npm run build
npm run deploy
you should make sure you put the correct aws profile inside the package.json file.