Installing Nano-control+ for iOS ism unfortunately, more complicated than other platforms.
There are 2 main methods for installing the game on iOS, both involving the use of a computer. AltStore and Sideloadly are the 2 I've found to be the most reliable.
I will provide a high level overview for these two, but for more specific details, you should look at the instructions for these tools on their own respective sites, https://altstore.io and https://sideloadly.io.
For AltStore:
https://ncplus.xyz/altstore
For Sideloadly: