Error when adding a domain, what should I do?

Question

open server

I have a php file with registration, it should run first when entering the site. The file is located in this path - OSPanel\domains\Project Friendly Letter\www. I go into the openserver settings and set the domain management to manual + autosearch. In the domain name I write - Project Friendly Letter, in the domain folder - \project friendly letter\www. I click add and an error pops up - Invalid value for the field: Domain folder , while the server is disabled.