Colleges determine who receives their own institutional aid several ways.
Most colleges review applications & select recipients based on merit: often on strong leadership, academic, or extracurricular strengths.
Other aid is awarded based on need & whether they student can financially afford to attend the school or not.
It is important to check with each individual college you're interested to determine what (if any) aid they offer, important deadlines to apply by to qualify, & when financial aid packages will be disbursed to applicants.
Many colleges offer financial aid from their own funds. Visit your school’s financial aid website or ask someone in the financial aid office about available scholarships. Colleges often have strict application deadlines for their aid, so be sure to get those applications in! And get to know the financial aid people at your school because there will be other opportunites available once you get there and declare your major.