The Geluntru Authority has a system to connect the entire galaxy easily, there's wormholes everywhere!

All wormholes lead to Uniter.
Each zone in the Milky Way has a "capital" planet host, for example, in Untruyun the capital is Hiperi.
On the capital, you will find every wormhole that connects to the rest of the civilizations, every civilization on a certain zone lead to their capital, and the capital leads to Uniter.

Colonies.
Many civilizations have colonies, to find them, you need to go to the civilization's home planet, and there should be another wormhole that connects them to their colony.

Example trip: Earth to DBSL1-3
Lets say you're a human wanting to go to the colony of DBSL1-3
To go here, you would need to:

Go to the Earth-Hiperi Wormhole, on Hiperi, look for the Hiperi-Doodebu Wormhole (DBSL are doodeburian colonies), and finally, when you're at Doodebu, you go to the DBSL1 wormhole. boom its that easy
(or you can just warpdrive)

Galactic Zones Aviable:

Untruyun
Central Zone
Abecon