Welcome to the forum and to EB, prepare for a wonderful gaming experience.

Some rebellions will join certain factions, so to speak, many joins KH, but Ankyra for example joins a Gallic faction, usually the Averni. I cannot recall the prerequisites, but I think it is depending on whether a civilised faction has built anything in it before it rebels.

In order to recruit in a city you have to build MIC (Military-Industrial-Complex) and to have a government. Each government has advantages and disadvantages and some does not allow you to recruit in some cities (Bononia has certain build problems until you reach a certain MIC level under certain governments AFAICR).
Buildings from another culture makes cities more likely to rebel BTW.

Confused? Look here:

1. Take city.
2. Destroy Barracks and sometimes Temples and like buildings
3. Build Regional Pacification.
End Turn
Next turn:
Start government
Some turns later it finishes (1-6 AFAICR depending on type. I often build an allied and that takes 1. Later replaced with a higher level.)
When it does either build Temples, MIC or whatever you need most.

When you have Government and MIC, you can recruit.

Have fun.