I think a word is missing at the end of this sentence. It should say "Silakan MASUK" shouldn't it?
Assalamualaikum is not correct? What is difference between Assalamualaikum and Waalaikumsalam?
Waalaikumsalam is a response to Assalamualaikum. So Assalamualaikum means "Greetings" as an initial greeting, whereas Waalaikumsalam means "and to you too" as a response.
The phrase "please come in" is "silakan MASUK" in Indonesian, not just "silakan."