In your DNS you have to add 2 A records and one CNAME. All according to Webflow instructions.
In your case the records you se on the picture
Then you should add a CNAME record the www as a CNAME pointing to the webflow SSL
The DNS can take up to 48 hours to update (normaly faster)
Don’t forget to republish your site after you have set the www domain to default
Here is another post i did