How to get Peach Aviation boarding pass

Hi everyone, I have a little problem, hope someone can help. I will be flying from Shanghai Pudong to Osaka Kansai airport and back, with Peach. There are 44 days left until the first flight. The company's site says I should provide a boarding pass when checking-in at the airport, but I don't know how to get it, as I can't find a way to check-in online, and 携程 (I used their app to book both flights) only sent me the itinerary via e-mail, not a boarding pass. Please help, thanks.