First of all you need to create a Twitch channel
After that get 5K Followers or get free ones (You can with less followers but with 5K you´ll have a lot more games), some people are giving for free here: Free Services and Giveaways and for buy you can buy here very cheap: https://followiz.com/
You´ll need to stream or make a video of some games, more streamings more games you´ll reach (You can download a gameplay and put it like it´s a streaming, be sure to get gameplays of little streamers)
You need to link your Twitch & Steam to your accounts in Keymailer & Woovit, Twitch in Epic.
In Woovit you can start getting 3 games that you want, you´ll need to make a stream or upload a video of one of the 3 games for get 3 games more and this always.
In Keymailer you´ll need to make a stream or upload 3 games in your channel, not matter the lenght. Then you apply to ALL the games you want!
In Epic Creator when you got accepted (With 5K Subscribers and few streams are easy) you´ll receive for free some of the games released in Epic Store (You´ll receive games after got accepted, not the previous ones)
If you want a game that aren´t in Woovit, Keymailer or Epic you´ll need to send an email to the developers asking for a key for stream, 90% will give you one.
So with Woovit you´ll receive 3 games for each stream that you make of one of the 3 games (It can be fake stream), let´s say you make a 20 min stream, you can get 3 Games that you want available in Woovit each 20 minutes!
In Keymailer it´s a bit slow, developers decide if give the game or not but there´re a lot more games.
Epic Creator is automatic, when you´re accepted you´ll receive games in your account when they release in the store.