Hello, I'm back, but with a solution for those who used the search bar function who may have got similar symptoms to me.
I managed to get Flarum to work on my Win Server, so here's the following solutions.
If you are given a white page with the text stating that Composer is missing cURL.
That means your Apache (for me) instance was clearly not loading cURL properly. For me, checking the errors.log in Apache/logs was enough for me and after googling the entire internet it came down to the fact that I was missing certain .dll's that required cURL to operate. I obtained these missing OpenSSL dlls through here: (https://indy.fulgan.com/SSL/)
Next, I was having issues with Cloudflare accepting the installation steps. That was due to timeouts limited by Cloudflare
This solution took a while, but all I've done was paused Cloudflare, extended the TimeOut option in the apache config, extended the timeout and memory limit in my php.ini and that should've done the trick. Once I've successfully installed Flarum via HTTP, I made sure to re-enable Cloudflare, re-tweaked my vhosts to accept SSL and 443 connections and modified the Flarum config to re-route all HTTP routes to HTTPS instead.
After that, everything is now working smoothly with no issues.
sizonov_stas Thank you for your efforts and your responses actually helped me with debugging the issues.