Ho do I access Windows.Storage and Open File picker for a WSA (uwp) App

I am trying to use a file picker plugin(File Management: Easy way to save and read files. | Input Management | Unity Asset Store)

Which works well for most of the platforms such as Mac/PC Standalone etc, now I have been trying to make it work for wsa, closest I have got to is to navigate the _Application.persistentdatapath _ but I am unable to navigate to other directories such as documents,downloads etc.
I searched around the forums a lot for this and figured out that Windows.storage API could be very helpful for me as it can also help me to use a Native File picker ( Open File Picker ) which could be even better than what I have been trying.
The problem here is that I cant seem to activate using Windows.Storage namespace

I am using Unity 2019.2.5 and following are my build settings

can any one help me with either a way to access the folder and files (possibly path like C:) and also how can I use Open file picker to launch a native file picking window ?

I figured it out by going through the Unity forum’s (Sorry Don’t have the link to the post which helped me)
What I had to do is simply change the Assembly Type in visual Studio
From - Assembly-CSharp
To - Assembly-CSharp.Player