The aim of impedance matching is to maximize power throughput. Your amplifier puts out a certain volt level and Ampere level. Together these produce a certain power level (V x A =Watts). And this is suitable for a certain ohm load.
However that same combination of volts and amps may not be the most useful combination for your 50 ohm load. It may not result in maximum Watts.
So you want to build a network (usually made from inductors & capacitors) with values which convert your initial combination of volts & amps into a different combination of volts & amps.
Only if you're lucky does the 50 ohm load already match the impedance, namely by maximizing power throughput. Or possibly you can revise your amplifier's L & C values while operating at your frequency of interest, so as to maximize power throughput to your 50 ohm load.