Question

Why did pope gregory VII and Henry VI come into conflict

Answer 1

I think it was  over who would control appointments of church officials, a conflict which is sometimes called the Investiture Controversy. Hope this was useful :P

Answer 2

The Investiture Controversy or Investiture Contest was the most significant conflict between Church and state in medieval Europe. ... The investiture controversy began as a power struggle between Pope Gregory VII (1072–85) and Henry IV, Holy Roman Emperor (1056–1106).