Trying to add a domain from one.com

Hello!

So I am trying to help a client to publish a website I made for him on Webflow.
His host is one.com and his previous website is connected to Wordpress.
Now I was trying to do everything as usual. After some hours I see the “connected” sign on Webflow and try to publish. one’s I publish it still directs me to the old Wordpress website and the “Connected” becomes “issues detected”.
One’s I unpublish it becomes “connected” again. Never used one.com but I am super confused about what is happening, can someone help?