When I activate it says Error: Invalid SteamID64?
This is normally because you have entered your SteamID64 in the wrong format when purchasing on the forums. You must enter it in the 17 digit numerical format known as SteamID64 and NOT a URL, or other type of SteamID.
You can easily convert to the correct one before you purchase by going to http://www.steamid.eu and entering your URL to get your SteamID64.
This is a SteamID64: 76561234567890123
This is not a SteamID64: https://steamcommunity.com/id/joebloggs
This is also not a SteamID64: STEAM_0:1:12345678
If you have already purchased a VIP slot, please contact Support at https://www.rustaforum.com/support and we will help you resolve this issue.