I have sent money to the account not registered in the app

No worries!

When you send your crypto using a phone number that is not linked to any existing account, we do create a note in our internal base that this amount is to be credited once an account is created.

A recipient will get an SMS prompting him to download the app and create an account with the phone number in question. Once he does that, he will see the crypto balance that you have transferred to him.