He ambitiously planned to start his own company within five years.

ambitiously 是形容词 ambitious 的副词形式，由 ambition（雄心、抱负）加上形容词后缀 -ious 构成形容词，再加上副词后缀 -ly 构成副词。ambitiously 表示"充满雄心壮志地、有抱负地"。