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: Log in to your Shift4shop.
Step 5. Go to content and select site content.
Step 6. Scroll down and look for Top Menu Links - click Edit.
Step 7. You can add page and named it as Affiliate Program, consider the sub-menu as new and then click add button.
After adding the page, at the righ corner, click on arrow down and select settings. In here, you can put the link of your registration link and then save.
Then reload your site so you can see the added web page where the affiliate registration link is added.