I try to copy a file from a GCP instance to my local machine, but powershell gives me a "Permission denied: (publickey)"

I created a GCP instance, and I created a private and public key on kali linux, I saved this key in the metadata of GCP, so I can access the instance through my kali machine. Then, I need to copy a file from this GCP instance into my local machine, so Im using powershell command: scp -i C:\Users\mymachine\OneDrive\Desktop\ myprivatekey GCPUser@GCP_IP:/home/GCPUser/lastname.txt c:\Users\mymachine\ But it gives me a publickey permission denied