With so many factors at play, it can be challenging to answer this question definitively. It depends on the complex size, the type of paint needed, how many floors there are, and the size of the team needed.
It’s worth noting that painting an apartment complex is not something that happens over a weekend. It needs scaffolding, sometimes traffic disruption, the goodwill of the residents, and dry weather.
You are probably looking at a month-long project for a team of five to 10 tradespeople with experience of heights and painting other tall structures.