Hello, I have an Adobe Creativ Cloud plan with this account, but I need to install it in another computer and it says that I can't because it's already installed in 2 other machines. So I tried to buy another plan, but it asks for a serial number that I don't have, and I can't find any redemption code either. I don't have any e-mails from Adobe from the time I signed up.
you don't use a serial number with cc. you use your adobe id.
and if you try and sign in to cc on a 3rd computer, you'll be prompted (and allowed) to sign out on your other two computers from that 3rd computer.
uninstall anything cc installed on that 3rd computer and clean, Use the CC Cleaner Tool to solve installation problems | CC, CS3-CS6
then install the cc desktop app on your 3rd computer and use it to install your programs, Download Adobe Creative Cloud apps | Free Adobe CC trial