Usually, the affiliate portal is loaded up on a separate domain. However, you can choose to embed the affiliate portal on your store.
In your Shopify control panel, click on Online Store, after this click on the Pages tab.
Now to create a new page click on the Add page button
In the Add page window, click on the code input mode (Show HTML) in the editor.
Here write the following code in the editor:
After writing the code, click on Save to save the page.