When looking at your possible purchase if the trailer doesn't come with brakes see if the brake mounting flange is on the axle
behind the hub. Usually a square flange with bolt holes for mounting. Absence of this flange you will need a new axle
(an expensive undertaking) or a good metal fabricator/welder to mount flanges to your existing axle
. Once you get the axle with a flange then you need to purchase a loaded backing plate kit and new trailer brake hubs to match your wheel bolt pattern. Then new bearings, races, seals and grease. Then you will need to wire the trailer for brakes and add a breakaway switch and battery
connection so the brakes activate should the trailer become detached From the car. If you buy a new axle get it complete with brakes you'll be happier in the long run.