Most often when you have to execute some PowerShell scripts through the GPO and you end up with an error on execution saying that the Execution Policy does not allow you to run un-signed script.
So you would need to create a new GPO to set the Execution Policy. Create a new GPO and edit it.
Computer Configuration/ Policies/ Administrative Templates/ Windows Components/ Windows PowerShell
Turn on Script Execution
Allow All Scripts
Move the GPO onto the respective OU, wait until the refresh or simple run
gpupdate /force on the computers.