Cannot get the cp command to work

[Edward-Ta]

I am trying to copy a folder to my server using this command:

{:ok, conn} = SSHEx.connect([ip: "my-ip", user: "user", password: "password"])
with {:ok, _, _} <- SSHEx.run(conn, "mkdir -p #{folder_name}"),
    {:ok, _, 0} <- SSHEx.run(conn, "cp -Ru #{path_to_folder} #{folder_name}") do
        Logger.info("path: #{path_to_folder} \n file: #{folder_name} \n Move Complete.")
	:ok
else
    {:ok, reason, exit_num} when exit_num > 0 ->
        Logger.info("path: #{path_to_folder} \n file: #{folder_name} couldn't be moved to server \n reason: #{reason}")
        :error

It successfully connects and creates a folder on that server.
Below I've done an example cp command using System.cmd that works perfectly but the cp cmd using SSHEX.run command keeps giving me this error:

iex(62)> System.cmd("cp", ["-Ru", "priv/static/assets/videos/example", "delete_folder"])                                                    
{"", 0}
iex(63)> ExampleProject.ExampleModule.move_files_to_server("priv/static/assets/videos/example", "example_folder")
:error
iex(64)> [info] path: priv/static/assets/videos/example 
 file: example_folder couldn't be moved to server 
 reason: cp: cannot stat ‘priv/static/assets/videos/example’: No such file or directory 

And I'm not sure what I am doing wrong here.