First Time Printer - Help with floating parts

Hello. I've just acquired an Ender 3 Pro printer which I'm super excited about and managed to print my first piece last night. I'm going to be printing a variety of Brio Wooden Train Compatible pieces to extend my children's collection. The first piece I've tried is here. https://www.thingiverse.com/thing:5186283 I've printed the non-Brim version. The issue I've had is that when it prints the two brackets at the top of the piece print poorly. I've attached the below picture. Each of these parts is free floating and not flat on the print bed. This is a necessity based on the piece. It also appears others have printed this many times with good effect. As stated I have zero experience but I'm confused about how this is supposed to work or what to do to improve it. Clearly, it's impossible to just put the filament in mid-air so how is this ever supposed to create a flat edge on that side? Again, I apologize for my inexperience Thanks

From the photo it looks like you have printed it flat on the bed, if that is the case you'll need supports under the two brackets.

The description on Thingiverse does say to print with supports.

It's good to see someone actually getting a printer to make useful things rather than novelty widgets.

you can try adjusting the boundary settings for a tighter fit - but I've noticed in cura the visual representation of the supports doesn't match the physical outcome - gravity exists out here, and the little gap ensures that it doesn't bind too tightly to the connecting surface and cause damage when removed.
you can always try a test print of just the upper section, just cut the model below the questionable support, and print only there up.
watch it closely, if it looks good after 10 or 20 layers, kill iit and print the whole thing.
this saves you time and effort and allows you to validate individual structures without waiting for the whole model to print.

Yeah use susport on prints like this. they can be turned on in your slicer for any prints with overhangs