Using AWS domain with Squarespace

Is your domain registrar Route 53? Can you describe the steps you have tried so far, and what error messages (post screenshots if it would help) you are getting.

This looks like it may be of help https://support.squarespace.com/hc/en-us/articles/360035485391-DNS-records-for-connecting-third-party-domains

Also these questions from a year or so ago sound like they are describing a similar scenario to yours, and the answers in them may help https://repost.aws/questions/QUniH4tVBuSd6v1qFqIgRraw/using-route-53-domain-with-squarespace https://repost.aws/questions/QUI8fClamWS0WdN1AV1ftAKg/domain-redirection-to-external-website-provider-squarespace-and-also-aws-ec2-instance-based-on-url