There are a number of ways you can use media in the Eheim Classic filters so it's really up to the user.
I've always used the Eheim Mech at the bottom as it traps larger debris that may get through the intake strainer, followed by coarse blue pads, fine pad and then bio media.
You could also do coarse blue pads stacked with a fine pad and then bio media.
Just remember the more fine pads or fine media you use, the quicker it will get plugged up, depending on the stocking level in the tank and amount of debris the tank produces.
There is really no wrong way as long as you have mechanical first, fine second and bio last AND you don't have the filter stuffed so full it either affects the filter flow or causes issues with closing the filter top.
Eheim Pimpette #270
Eheim Pro II 2028; Classics Series -2215, 2217, 2260, 2262; Pro 2229 Wet/Dry