I talked on live chat to Citadel Servers and they have stated they support Ark Server API and one click installs.
Looking into it, nitrado may support ark api but not sure, attempted to reach out but there is no live chat.
EDIT: Nitrado do not support ark api, this is confirmed here
I am now on day two of trying to get support from them on a rented ark server. The one click downloads are all out of date and the server will not function. I have submitted 4 support tickets. They also charge you $20.00 extra for premium support and then provide nothing. I would not recommend this server or company to ANYONE at this time. I will update this if any action is taken to rectify the situation. I will also post this everywhere I can find to make sure that no one makes the same time consuming mistake that I did.