HostedZone for a domain in squarespace

Hello.

What is your question specifically?
Does this mean that I cannot access it with the Amplify domain set in Route53?

I created a hosted zone on AWS Route53 for my domain that I bought on SquareSpace and then entered those 4 Nameservers to Squarespace. After that, I followed the steps on amplify and successfully created the SSL certiface and was able to connect the hosted zone to my amplify app.

I think you will be able to use it if you rewrite the NS record.
If it cannot be used, it may be taking a while for the domain to propagate, so why not try resolving the name after a while?

You can check the domain propagation status on the following sites.
https://www.nslookuptool.com/