予定通りに到着するようにして下さい。
- Please make sure to arrive as scheduled.

予定通りに到着するようにして下さい。 meaning: Please make sure to arrive as scheduled.

予定通りに consists of the noun 予定 meaning schedule or plan, and the grammar pattern 〜通りに which means "in accordance with" or "just as". ⚫︎ The particle に is used to indicate the manner in which the action is performed. ⚫︎ It shows that the action of arriving should match the schedule without any deviation.

The particle に attached to 予定通り functions as an adverbial marker. ⚫︎ It turns the preceding noun phrase into an adverbial modifier that describes how the action of arriving should be carried out. ⚫︎ It is essential for connecting the adverbial phrase 予定通りに to the verb 到着する.

到着するようにして下さい contains the key N3 grammar pattern 〜ようにする, which means "to make sure to do" or "to try to do". ⚫︎ The verb 到着する is in its dictionary form to precede ようにする. ⚫︎ This pattern expresses making a conscious effort or establishing a rule to ensure a certain action happens.

The verb 到着する is a suru-verb meaning "to arrive". ⚫︎ 到着する changes to 到着するよう when connecting to the grammar pattern ようにする. ⚫︎ The dictionary form 到着する acts as the base form before adding ように.

して下さい is the standard polite request form used at the end of the sentence. ⚫︎ It is formed by combining the te-form of the verb する (which is して) with 下さい meaning "please do for me". ⚫︎ Combined with ようにする, するようにして下さい politely instructs someone to make an effort to fulfill the request.