Does that mean I will need a converter to lower the voltage output but my question is what happens with the load's current draw?
Yes, unless you want your motor speed / dynamics defined by how full and warm our batteries are, you will need a controller of sorts.
Does it affect the design of the converter?
Is it possible to build such thing?
Well, yes. I mean, people manufacture cars that draw a lot more power from their battery packs.
Is it even worth it?
45 A is a hefty current if you need to control it with semiconductors.
But, then again, that's about 500 W; not incredible little, but I could imagine it's somewhere in the region that Pedelec bicycles do.
I don't know what "worth" means to you.
any other suggestions?
All batteries are designed for different things. Most 18650 cells will seriously overheat and likely catch fire and explode if you drew 45 A from them! So you'll need to put multiple cells in series (to reach your 14.8 V), and then put multiple of those in parallel (to reach 45 A). That requires cell balancing, making your overall system even more complicated.
Also, remember, you're not shopping for the highest energy density per unit of money, but for the highest power density, very likely (depends on your use case, but yeah, at 500 W power, you won't be using a second market laptop battery).