After clicking the primary modpack download button and being hit with a fake "Update your Chrome!" crapware download page, followed by a "Update your Java plugin!" crapware download page, I am really getting the hackles up regarding your custom "Ikara Pixelmon launcher".
I have a special place where I put all games, C:\Games which is set with NTFS permissions:
Users - Full Control
So Administrative privileges are not required to install games here. I provided that to the launcher:
C:\Games\MC\PixelMon\Ikara Launcher\
And yet the launcher STILL demands Admin elevation to install. I declined.
Sorry, but after those malicious advertisements, I don't trust your installer to not also install unwanted junk on my system. What exactly does it want to do while installing this modpack?