My Game won't open (Mac 2018)

So this has happened around 3 times now. Every so often, I'll come home from school and try and open league. The computer has been in sleep mode for the entire day pretty much. I'll try to open up the game from both the dock shortcut and the applications folder. After I click the game, it will bounce for a couple seconds, then give me a "League Of Legends quit unexpectedly" notice. If I redownload the game, it starts working again, but the download takes forever. Does anyone have an idea how to help?