If you have acquired a domain from Squarespace, you should follow some activation steps in order to connect the domain with Short.io and use it for link shortening.
Important note: If you use it as your main domain for your website - please configure a subdomain instead.
Squarespace configurations
Sign in to your Squarespace account.
In the top left corner of the page click on Domains:
Click on the domain that you want to connect with Short.io:
In the Overview panel click on DNS:
In the DNS Settings you need to delete all the unnecessary defaults for the domain by clicking on
and then on Delete in the popup dialog:
Click on Add record.
In the Custom records panel fill in the following information and click on Save.
Host: @
Type: A
Data: 207.174.61.1
The result should look as follows:
Tip: If you want to delete or edit a record, move your mouse over it
to display the options:
and 
Short.io configurations
Sign in to your Short.io account.
Open the User menu and click on Add domain:
In the next screen click on Add my own domain:
Enter your domain name, select the option This is empty short domain (sub-domain) just for links and click on Add domain:
Open the Domain settings and check if the domain is in status Active:
Important note: If the domain is Inactive then wait for a few hours and click on Refresh to check if the status has changed.
You will receive an email from the Short.io team informing you that the domain is now configured. Feel free to shorten your links and enjoy Short.io.