Shades of Agent Smith.
No, they would just need an inexpensive, faster then light propulsion system, and lots and lots of room, within a few thousand years they would take up a number of galazies.
Apparently you assume that million-year-advanced volitional/conscious beings would be stagnant with the level of technology no greater than achieved by Earth beings.
Just from looking at our advances with quantum computation, quantum entanglements and nanotechnology it points to the highest probability that advanced technology beings transfer not the physical self or object, but rather, the information is transferred and the object or being is recreated at the distant destination. Near instantaneous recreation across the Universe making c a seemingly comparative standstill.
If every conscious being that has lived on Earth was immortal and continued to procreate since the discovery/invention of consciousness on Earth -- about 3,000 years -- there'd still be plenty of room in our solar system for additional procreation of volitional/conscious beings.
Nonetheless, with their millions-of-years or billion-of-years more advanced technologies, the ability to control the Universe implies the ability to create new galaxies -- perhaps even create Universes. Whatever it takes to preserve the most valuable entity in existence... The controller of existence--volitional/conscious beings.