I don’t know who designed this poster template, but I love it. By looking at it you can see that the designer has prioritized the information in order of importance, then employed a set of constraints to convey the message in the simplest way possible. The set of constraints are made up of three elements: color, size, arrangement.
PRIORITIES. You know a that a designer has their priorities in order if their work passes “the squint test.” That is, if their reader squints at it, they know what it’s about. Readers don’t need to know all of the information at once. They need to know the most important thing. Then, if the most important thing is interesting to them, they will move closer to the poster to get the details.
CONSTRAINTS. Designing something that is clear takes discipline. Effective designers use constraints to get their point across. Sure, they could use every color in the rainbow, but in most cases, that just confuses things. Sure, they could make all of the type close in size, but then how would your reader know what information is most important? Sure you could arrange elements all over the page equally, but then how would your reader know what to read first?
The most common pushback I hear from junior designers on constraints is that they limit creativity. I don’t know where this idea comes from but it’s false. The best artists and inventors use constraints. And you should too.