What is the meaning of 凝聚人心？
众筹 -- 

众 means many people; crowd;

筹 means plan and prepare; 

众筹 in the context means plan and gathering money from many people to buy a house. 

‘凝聚人心’的意思是什么？ Bring the people's hearts together, so they can act as one unit and contribute together. 

发起人initiator is trying to emphasize that more important thing than gathering money to buy a house is to bring the people's hearts together by doing so.