That's awesome.

You are at a first stage of building a MOOC, a Massive Open Online Course portal.
https://en.wikipedia.org/wiki/Massive_open_online_course

I worked in the growth team of a UK startup that reached an explosive growth in 2015.

I like your approach you applied the "don't scale" approach in the Paul Graham (Ycombinator founder) way.
http://paulgraham.com/ds.html

I invested in this kind of business hundreds of thousands of dollars every month on several acquisition channels.
The good news for your business is that bidding costs for Indonesian users are the lowest in the market today so you could leverage this opportunity to invest in CPC/PCM channels.

There is a really important thing you will need to do before doing this. Building an email list at the top of the funnel.

To learn how to grow your business today call me and I will help you.

Ciao
Danilo