How to access mission planner software?

I tried several of the possible way to access and download the mission planner software. All I got was a notice that the page was not available. I would like to buy a APM 2.8 flight controller but I need to know that I can program it.
Thanks for your help.

Just read this ardupolit. I got my copy here:

Or from here and re-think buying an APM Flight Controller. Those have been obsolete for years.

APM 2.8 is obsolete, not supported anymore. Do yourself a favor and get one of the new boards.