5 vs 15 -----is the electrical current it can store
If the wrong run capacitor is installed, the motor will not have an even magnetic field. This will cause the rotor to hesitate at those spots that are uneven. This hesitation will cause the motor to become noisy, increase energy consumption, cause performance to drop, and cause the motor to overheat.
That 50/5 capacity will cause issues the longer you use it.....
A quick Goggle shows Dometic 50/15 Fan Run Capacitors available/in stock ready to ship