You haven't received an SMS login code to your mobile device as expected. You have a phone with iOS 12 installed.
When Apple released version 12 of iOS in September 2018 they added some SMS spam filtering features that apps like Truecaller are taking advantage of to filter away unknown senders.
Go to your messages. You should see two tabs here after this latest update, iMessage & SMS and SMS Junk. Click on SMS Junk to view the message from Astrid.