Permission denied(publickey) when I try to move local file to ubuntu

I'm trying to move my local file to ubuntu server

scp /Users/jaeuk/Python project/MarketTimer/MarketTimer_1.1.py ubuntu@public IP:/home/ubuntu

at the first time when I do that I get this output:

The authenticity of host 'public IP (public IP)' can't be established.
ED25519 key fingerprint is SHA256:*****.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'public IP' (ED25519) to the list of known hosts.
ubuntu@public IP: Permission denied (publickey).
lost connection

and it keeps printing same output:

ubuntu@public IP: Permission denied (publickey).
lost connection

You should have verified that you are using a keys pair for the local user in your client that its publickey is allowed by the server for the user ubuntu in the /home/ubuntu/.ssh/authorized_keys file containing the public key of your local user pair of keys.

Runing the following command in your ssh client:

ssh-agent sh -c 'ssh-add; ssh-add -L'

You will get the public key file content that should be included in the /home/ubuntu/.ssh/authorized_keys file in your remote server.

If you can't access to the server you can't verify the ubuntu user authorized_keys content, so you will be able to add rebooting in rescue mode and mounting the file system with chroot or add the public key via a web dashboard of your server provider.

If you have verified that your public key setting are really ok or in any case that it still not working please run:

ssh -vvv ubuntu@public_ip

and/or

scp -vvv /Users/jaeuk/Python project/MarketTimer/MarketTimer_1.1.py ubuntu@public IP:/home/ubuntu

It should show you a lot of more useful information for know what's happening. You can paste the results for get more help about your specific case