When SimCity BuildIt was announced as a Freemium mobile app there were a lot of groans and disappointment among long time fans but while it does change the essence of the gameplay the app remains immensely popular among new and old fans alike for the simple reason that it is playable without much need for the Freemium SimCash currency.
Most players are able to play the game just fine using regular old Simoleans plus a decent amount of patience and some time trading their way through Global Trade HQ for what they need.
The primary use of the SimCash is to speed up gameplay by reducing the timers that set for factory and store production of items or for fast-tracking construction of docks, airports etc.
It is important to conserve any SimCash that you receive and maximize their use for supporting expansion, storage or other long term and lasting game supports rather than wasting them on paying of factory and store timers which will disappear with time and patience anyway.
However there are two ways of getting free SimCash:
You are given it for free upon starting up a new game of SimCity BuildIt (you get about 50 SimCash to get you started/hooked).
You can win many hundreds in SimCash just by completing simple City Achievements like trading, importing, expansion of land, getting Facebook friends etc. It is with these City Achievements (accessible by clicking on the Mayor's Mansion) that I keep a steady trickle of SimCash in my City's coffers.