can't find an old illustrator version

hello community, i need help with illustrator installation.
i have a macbook pro 13 inch mid 2012 and illustrator 2020 works fine, the issue is that i had to fix the computer and i had to install everything again and now i can't install illustrator 2020 anymore, it asks me for the latest software update (i have iOS mojave) even so if i update to 10.15 it still won't work. can anyone give me a solution? i can't change computers at the moment and i really need to work with the program. i'm freaking out