Since you are a namecheap hosting customer, you could try to request a free certificate (comodo positive ssl) from your cPanel (Namecheap SSL)
or
go to sslforfree.com / zerossl.com (both are fine), follow the instructions to create a certificate & download it.
Actually i forgort the link from where i allowed ftp permission to create folder and then they putting content in that folder in my site .
have u remember a website which provides 2 ways to install certificate , one is to provide ftp details and other user will upload files in the folder by themself.