General Toad Required Windows Privileges:
At a minimum, in order to install and run Toad, make a connection and do basic operations, you must be a Power User and have read/write privileges on the Oracle homes directories that you use for your connections. If you are a Power User, you will additionally require read access to the Oracle client folder.
Toad Citrix Install Required Privileges:
During installation you will need Administrator rights to the local PC since Toad requires write access to the server registry during installation. But it should only need read/execute access to the server registry and the Toad install folder for daily use. Once Toad is installed in the CITRIX server, users must connect to this Toad instance through their Citrix logon.
Toad requires read access to the Toad Installation directory, HKLM\Software\Quest Software\Toad in the registry and the Oracle directory. Under Toad.exe Properties | Compatibility tab | User Account Privileges, make sure the Allow non administrators to run this program box is checked. Write access is required to the Oracle directory if any of the users want to edit the tnsnames.ora file by using the TNSNames Editor. When you choose a Citrix installation, all users' files are stored in a user_name directory. When a Citrix user opens Toad for the first time, Toad will copy the contents of this folder to the user's associated Application Data folder for Toad and should have write privileges to this.
More information and details can be found in the Toad Getting Started Guide.