Making my first container gardening soil

Complete newbie here I just posted something recently about my seedlings being too leggy. I guess the only way to learn is to screw up. I bought a cubic yard of compost today and I don't want to screw this up.

I live in Northwest Florida and I live in the city and to build up my lot on a hill, they trucked in clay so after about 6 in of low quality topsoil it's orange clay. So I decided that I was going to try some containers and raised beds. I realized that trying to fill a container or raised bed from stuff at Lowe's would bankrupt me.

I still don't really understand the difference between soil and compost, but I went and got this from their local nursery and they said they pot their plants with this. It's very black and smells good.

Looking on here and on the internet in general, there's a million different recipes for container soil. I don't want to overcomplicate this. I'm not starting my own nursery.

I asked the lady what was in this and she said it was composted wood products, pine fines, milorganite, and mushroom compost.

So the question is do I still need to add some stuff like perlite, dirt, sand, coir, vermiculite ,etc , or is it good like it is? Would this be too dense after you water it? it's definitely not as light and fluffy as something like bagged potting soil.

I plan I'm doing any mixing on a per container basis, or at least a wheelbarrow.