The site you linked to works (relatively) fine for me:
What’s left now is to go to your WordPress admin dashboard and change the site URL from systemicastrology.infinityfreeapp.com to systemicastrology.com for the content to appear correctly on the new site.
I don’t see why not.
You only need to change your domain’s nameservers to InfinityFree’s to be able to add the domain to your account. After that is done, you can change your nameservers back to Namecheap’s, but you will need to create DNS records there to make the site point to this hosting.
The tutorial on how to implement Cloudflare covers the process, I’ve modified the wording a bit to match Namecheap’s platform:
This article can help as well: