Literally translated, 立己达人 means that just as you would like to establish yourself in the world, so allow others to establish themselves. The closest equivalent saying in English is "live and let live".

If you wanna get success, you should make others success at the same time. When you share the goodness with others, then you gain the genuine goodness. It's a great thought in China.

it is the short form of the motte "己欲立而立人，己欲达而达人" by Confucious, meaning "If thou wilt to establish thyself, establish others; if thou wilt to prosper thyself, prosper others".