Hi Alba!
So, unfortunately no, WaniKani does not have the ability to learn by the standard grade levels. They have made their own unique order.
You can see how much of each grade level you know by each level of WK by going here: wkstats and then clicking on Charts and then Joyo.
Grades 7 through 9 are all lumped together, as those are the kanji Japanese people learn in Middle School. 「中学」
WaniKani will teach you your first kanji after you’ve gotten your first radicals correct 4 times (each). This is called “Guru”-ing your radicals. You need to get them to the Guru level to unlock the associated kanji. You need to Guru 90% of your kanji to unlock the next level. Please go read the FAQ and Guide again for more answers. ^^
You can also see this thread: New People Questions! ~~~<3 [Lost?! Confused?! We're here to help!] It has links to both the FAQ and Guide, and answers to other questions you may have.