For my project I want to make a sync between my Icloud calendar and a Wordpress plugin written in PHP. I see a lot of information about sync's in Eventkit, but as I understand this is only useable for IOS platforms. Is this correct? And are there any other solutions to get the job done?
You can create a link for your calendar (https://support.apple.com/kb/ph2690, with the steps provided for creating a publicly shared calendar). Once you have this, replace the "webcal://" part of the link with "http://" and you have the data you want to use. This data is in caldav format though, so you will still need to interpret it in an appropriate format (https://en.wikipedia.org/wiki/ICalendar#Technical_specifications has some documentation on how to interpret the output file).