You don't put ads on your videos yourself; Adsense does.
So if you don't have an Adsense account, you won't even be allowed to apply to the YPP. I don't understand how you could have a Monetization feature which says "Monetize videos with ads" if you haven't applied to the YPP. Please give us a screen shot of what you see at the following links in your Creator Studio...
https://www.youtube.com/features
https://www.youtube.com/account_monetization
Addendum: You have no videos showing! No videos, no possibility of joining the YPP, as you have no media to monetize in the first place.
You need 1000 subscribers, and 4000 hours of watch time in the past 365 days before you can be reviewed for monetization eligibility. Your channel is only 35 days old, has no videos uploaded as yet so no watch time at all, and only 21 subscribers.
You need to at least upload some content before you start thinking of making money.