Toolbar isn't really supported in frontend. In backend it's rendered by mod_toolbar module which is only available in backend.
You can still render the toolbar in frontend using this code but it may not necessarily work correctly:
Do you want your users log in front or backend of your site?
The workflow is a little different for each scenario.
What user functionality you want?, or want to extend?, once the user has logged in.
To provide this to your users you need already establish your user groups.
The first case: if you want to provide a "user menu" in the front-...
First of all, you're using different file structure and class naming conventions than Joomla! core. This won't work without rewriting related methods such as controller's getView().
That said, using standard naming conventions, I was able to get this to work by setting base_path option when fetching the controller in component's entry file:
$controller = ...
I would program a custom module for this purpose.
In its helper file I would load the Model of your component to retrieve the items that you will display.
Check out a Joomla core module like /modules/mod_articles_latest to see how it re-uses Joomla's ContentModelArticles.
In the /tmpl/default.php I would put the html + php to display the data. As basis ...
I have been fighting the same problem for two full days now, going over lesson 10 of Robbie Jacksons excellent video explanations in this series https://docs.joomla.org/J3.x:Developing_an_MVC_Component/Developing_a_Basic_Component again and again.
In lesson 10 he tries out his own alternative approach and he comes up with this redirect in his subcontroller ...
The approach given above seemed like it should work because it does. However, if your class is a little more complex than my example and you have a __construct() function don't forget to call parent::__construct() or it won't initialise the list of paths to search for your custom views and you will end up with this error message.