If you buy a Blu-ray drive, make sure it comes bundled with software. Most come with BR player software, and many with BR creation software. You should be able to natively burn and read files on BR with most modern operating systems.
Avoid buying "OEM" drives. Some OEM drives may include software. But it's hit and miss what's in the box, even within the same brand/supplier.
Once you have the drive and software up and running, then you can decide if you need to actually buy separate software.
The first thing you’ll need is an external Blu-ray drive. There are several available including models from Buffalo, Samsung, LG, ASUS and Sony. Hardware wise, there are plenty of drives available. I got one of these, but there are plenty of others. Don't think it needs to be anything special The Best External Blu-ray Drives | The Wirecutter
As for the software, anything that's fully functional (and legal) isn't going to be free, because the DRM tech needs to be licensed and that costs the software vendor money. But you can choose a relatively cheaper one like Macgo Mac Blu-ray Player.