Based on your firewall settings, you could have the launcher bloked from the firewall, unable to update file ecc..
To fix this follow the steps below
Step 1 :Search "Firewall" in the search bar and click on it
Step 2: Click on "Advanced Settings"
Step 3 : Click on "incoming connections" > "new rule"
Step 4 : Click "program" and then "forward"
Step 5 : Click "program path" and then "browse"
Step 6 : Move to Aion folder, and select EuroAion Launcher then click open and after "forward"
Step 7 : Click on "allow conection" and then "forward"
Step 8 : Tick all and press "forward"
Final Step : Insert whatever name you want and hit "forward"
Repeat this process for "outgoing connections" from Step 3, and you good to go.
If after this,you are still unable to get update from launcher, you should check your Antivirus or Modem Firewall settings.