It's going to be somewhat difficult to both redirect or point your domain to a subdirectory or another directory while you get wordpress sorted out on that domain while keeping one-click status for that domain.
What do you think you need to "sort out" about wordpress on your domain? Is it content and organization? Plugins? The theme?
First, create a subdomain and install Wordpress there. Use that subdomain to practice getting everything right for how you want to configure Wordpress. You will be able to export all content you set up and import it into your final Wordpress installation on your domain.
Second, decide whether it's more important to keep one click status and take a small amount of downtime or to have no downtime and to lose one-click status.
If you want to keep one click status, you'd get everything going on your alternate subdomain, then quickly do the one-click install, setup and import of content into your main domain very quickly in the "off hours".
If you want to have zero downtime, again, you'd get everything going on your alternate subdomain, change the configuration of Wordpress on the subdomain to make it think it's going to be the main domain, then change the web directory of the main domain to be the directory you installed wordpress into.
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