Solar Contractor for AC Off Grid Power Plant in Papua?

There are people who will arrange for Power purchase arrangements. Then you do not need the initial capital as well. But you will need a good credit rating or be backed by the Government.
As you need off grid power and you will need the AC power all the time you will need storage Batteries and inverters of this size.

Then definitely the cost/Wp will be higher in the range of $5/Wp unless you have your own battery backup system already with you of this capacity and diesel Generators.
Your load cannot be constant 2MW all the time. It will be a night peak load mainly for lighting. You can reduce on the diesel generation if you have one already. You could use the DC generated and use DC from the battery as well with DC diesel Generators it will be much cheaper unless you want to transmit to long distances by stepping up the AC voltage
Although your question is very simple the reply will need detailed study of your load profile requirements and availability of sunshine etc.
You may have to appoint a good reliable consultant to study and report.

A standalone AC system will cost more than $3/Wp and you will have to contact people like this to get PPA signed. You credit rating will have to be high
Alternatively get down the reliable solar panels which are low in price $1 to $2/Wp and assemble your own way with necessary connection charge controllers Battery and inverters. Have your own local good consultants. This will give you the lowest price like $3000/kWatt installed.

As you are close to China and Honk Kong you could find people from there to assist you, Australia is also doing good work on solar projects.
It may be possible to go for your own diesel generation or coal power plant for your 2MW power requirements which will be cheaper as you have cheaper fuel from your country or Indonesia.
Is this for your institution or for the city or for a factory. Then only when full details given one can plan further.