You should NEVER be using TAS6EVO.EXE anymore.  It is outdated and not compatible with the current programs.  You need to be using EVOERP.EXE.  But when you double click on EVOERP.EXE in DBAMFG when  loading a new workstation, it should not go to the logon screen.  It should run the Workstation Setup and create the C:\ISTS folder, copy the necessary files, and the desktop icon.
 
What is the 4th line of the TASPRO7.INI in the DBAMFG folder?  It should be
 
DfltRunPrg=X:\DBAMFG\EvoWkssetup.rwn
 
where X:\DBAMFG\ is whatever your server path is.
 
As for the user rights to C:, if you are going to have multiple users sharing the same workstation, then you will need to configure it using the instructions for Terminal server but in a normal single person at a desk type environment, you should have the user profile run the installation so they will be the owner of the C:\ISTS folder.