Once you get the proxy list, please wait for 10 minutes for the changes to take effect and then start using the proxies.
If you are using IP authentication, make sure that you have added your internet/server IPs through which you will be using the proxies to the authorized list.
If you are using the username and password-based authentication, please make sure to set a password for the proxies as the username/password for the proxies is different from Dashboard logins.
NOTE: It takes around 10 minutes for any changes in the panel to take effect.