How do i install photoshop? Help!

I bought my mensual plan for photoshop and i don't know what im supposed to do now?? I got an email confirming my order and it said that now i had to install the creative cloud app and then just chose the application i bought and press download, I did that but when it was done downloading it said `trial expired``. i had previously downloaded the trial version but i just bought the thing so I don't really know what I'm suppossed to do?? I tried unintalling the app and the cretive clod as well and downloading again but it keeps saying ``trial expired``also when i try to open it it asks for a serial number but i never got one like?? Am i suppossed to get another email or something?? i mean i bought it from the official adobe page so i don't understand why this is happening?? I really need the program like i have tons of homework? Do i have to wait or something? Help