Some good looking things in here to help incentivize teams to develop young talent:

After two years and over 200 hours of qualifying oversight -- the exact number of hours varies by age and situation, sources said -- a team can sign the player and receive significant salary cap relief as a reward for developing the player.

Also, developing a young player can be beneficial even if you don't sign them yourself:

If an NWSL team develops a player under the PDR mechanism but she signs with a different team inside the league, the NWSL team that oversaw her development would still be rewarded with salary cap relief (to the tune of around half that of signing her, but also varying, sources said).

This helps avoid some of the problems seen in previous youth development programs:

Prior to the new CBA, players had limited agency and their rights were a free-for-all due to the NWSL's antiquated "discovery" system that allowed teams to "claim" players who they had not previously engaged to sign.

In the early years, those discovery rights became assets for trades that would, at times, block signings by opponents. Teams would also hold onto "NWSL rights" while players were signed with teams abroad.