the error message is not related to the version you're using. Your account needs to have Administrator Rights otherwise you won't be able to start the Execution Server. Your System Administrator should be able to grant you Administrator Rights.
In order to have multiple machines as Execution Servers you will need additional Test Studio Standalone
/Test Studio Vs-Plugin
licenses. RunTime edition is probably the best choice since it costs only a fraction of a normal license and it's designed only for running tests. You will need an additional license for each machine you want to use as an Execution Server. Please note that you can still use Scheduling with only a single license but the Scheduling/Execution server will both need to be running on this machine.
Please let me know if you have any additional questions.
the Telerik team