I saw on another post that i think have the same problem and i found it cause i have it too.
The post: "Hello guys, I recently received an email from EA's Play Test to play Skate 4 in July. I signed up this morning, which made me very excited. However, just now I went to the EA Playtest portal home page and it no longer appears in the "Update Playtest" section. When will I be able to play Skate 4? Something that used to appear before. Has this happened to anyone else? I can't even sign up for the game again :/ Can someone help me?".
There was then a community manager who responded with: "Hey. If you don't see the playtest, it means you're already signed up. You just need to wait for an email with more details. That will arrive before the playtest starts on July 2nd.".
Hope this helps