In general, most front forks for bikes are 100mm wide. Some smaller folders are only 80mm. Many fatbikes are 135 mm wide. You're the only person who can tell us tell us how wide your fork is, Measure it and also use a magnet to find out if it's steel or alloy.
What kind of battery did you get for 50 bucks? What voltage is it? Does it have an Ah rating?
What kind of conversion motor did you buy? Yeah sure, why keep it if it's not going to fit. Most front motors will fit a 100mm wide fork, unless you bought a fat bike motor or a rear motor.