Help on Arduplane compatibility

I want to apologize for my lack of knowing, but I am eager to learn more about this field. My goal is to build a fixed wing UAV. Recently, I purchased a kit that composed of the following:
-APM2.8 Ardupilot Board
-Mini OSD
-Telemetry Receiver/Transmitter
-Power Module

On ardupilot’s site, they state that the APM2.X boards are at end-of-life. That they no longer support plane builds past 3.3.0.
I setup my APM2.8 with a plane firmware loaded from Mission Planner. The firmware version is 3.6.0. Will this be create an issue with the software or issue? I would really appreciate if anyone could share their opinions and experience with building a fixed wing UAV.

I can’t seem to find in depth guides suited for beginners that explicitly explain the building process (both hardware & software). If you might have knowledge of such a thing, or any link with good information; please share. Half the battle seems to be finding the information.

Thank you for your time!