I think the problem might be the limited access rules on the user. You should work with the Account (which is a specialization of the user). In order to get the account, you can add an inheritance split to your microflow and cast to Account (in case of Account). Return the Account object and use this in your dataview. On the Account, you can change AccessRules if needed. On the user you can’t.

Since Account object is a specialization of the user object in administration module. Return the account object and use this returned object wherever you need

Thanks for your quick reply and support. 

The focus of my issue is: I don’t know how to display the variable $Account on the web view – which Widget or other component allows to show the variable content?

You can create a data view, with source microflow, in that microflow you return the current account, and on that data view, you put a text field with the attribute name (or firstname + lastname) of the account

Thanks Yehoshoua – the data view hint was exact I was looking for!!! Now, it works:

Many thanks to all of you for the support,

best regards

Bernhard