Hi, @Skj0ey
That error was a temporary & general problem. That could be some issue with your internet connection, please try again.
If it still doesn't work, You can try to use this methods:
Press the Windows Key + R (Win+R) on your keyboard
Enter "%programdata%" and press Enter (without the quotes)
Find the folder "TruckersMP" and delete that folder.
Navigate to C:\Program Files\ and delete the folder named "TruckersMP Launcher"
Go to our website and re-download and install the Launcher with admin privileges https://truckersmp.com/download
Open The Launcher with admin privileges and click "Install Available Updates"
Hope I can help you.
Sincerely,
Tony