Step 1: To get the link to the Sign-up Page, from the Admin Dashboard click on "Configure Sign Up Page".

Step 2: On the following page, click the link "View Sign Up Page".

Step 3: You get the Sign-Up Page where you can copy the link from the Address Bar at the top.

Step 4. Login to your Squarespace admin account and hover-over your site and click on Edit Site button.

Step 5. Click Pages and go to the page where you want to embed the sign up form.

Step 6. Click on Edit Button.

Step 7. Add section under footer. 

Step 8. Fill in the text and Paste the link in the field provided and click on Set.

Step 9. Click Done and save.

Step 10: Reload your site and you can view the new menu added to the Footer shown below that will redirect to Sign Up Page.