It may be caused by 1 of 2 reasons:
1. You have entered the wrong address (typo)
2. You have never registered this account on infinito app.
There are many our old users who did not sign up for an account, but accessed to wallet by using passphrase/ private key.
Please kindly check if you received an SIGN UP email on Infinito before.
If you have passphrase, please kindly follow the anonymous flow as below: