Welcome to the world of caveat emptor.

Most bagged products (topsoil, compost) are poor substitutes for "the
real thing". You have no way of knowing exactly what went into this
stuff, and in my opinion, it's a bad sign that the mfr recommends
against planting in it. My experience with bagged products of this
variety is they typically come from a waste management operation.

It's true, real manure is planted in - although best if composted,
definately not raw - and it is a great soil conditioner. But like all
soil conditioning, it takes TIME and TONS OF MATERIALS

Seriously, I mean tons of materials - depending on your starting soil.

The manure I use is at least 1 year old, dusty-dry, crumbly,
absolutely no odor. Mixed into the top 3-4 inches of soil it just
disappears. You could try splitting open the bags, letting them dry
out, and mixing into your soil lightly.

So here's the leap off the deep end:
You can plant directly into straw, although it might be tough to come
by in your neck of the woods. If you bury the bale half into your
soil, it will speed decomposition and get your plant roots down into
the ground. If your city has a composting program, check into it.
Visit, see if you like how the material is handled. Woodchips/sawdust
in quantity can be had from sawmills, cabinet makers, wod workers...
Yes it depletes nitrogen in the short term, but again, over time, is a
great soil conditioner. Talk to your city officials about leaf
recycling - maybe they can cut you in on the action.

I'm sure others will be by with (shorter) additional comments..