How to bring in Username (or First name / Last name) onto Process Email Template? (Enterprise v10.2 on Sugar Identity Management)

All these fields are replicated from IDM to Sugar. So if you know the names (first_name, last_name, user_name,...) you can use them in BPM email templates like {::assigned_user_link::first_name::} got this assigned {::Accounts::id::} ... 

I do not know why they are not shown in the selection during the template definition. Must be a bug.

Thank you Harald Kuske...  I still do not have the option of first name, last name, username though?

Thank you Harald Kuske...  I still do not have the option of first name, last name, username though?

Yes you still do not have the option to select these fields but you can use the the placeholders when you write them yourself just like {::assigned_user_link::first_name::}. Select any field, add it to the text and then replace the field name at the end between the two :: separators by the filed name you want to use.