How to stop users from getting redirected from my website


I am very new to phplist and have just installed this software yesterday in my shared hosting server. I created a newsletter subscription form and using a popup plugin from wordpress I was able to generate a popup for the newsletter form succesfully. The issue that I am facing is, the users are getting redirected to my subdomain where I have installed the phplist instead of to my website. Can you please guide me on how to ensure that users will remain on the same page after subscribing instead of getting redirected.