Is there a file management system in TrueNAS Scale?

[Flo]

TrueNAS itself does not have a filebrowser built-in, you can access your data via an SMB share for example. For this you should create a new user and then give them access to the dataset / pool you want to share. Then you can mount the share in windows and log in with your created user.
Here is a tutorial that explains each step in detail:

How to create a SMB Share in TrueNAS SCALE - The basics

and here is a tutorial from the TrueNAS docs:

Adding SMB Shares

here are also the long SMB docs if you want more info about the whole thing:

Windows Shares (SMB)