Every time I boot up my iMac "... is an app downloaded from Internet. Are you sure you want to open it?" I get this popup every time I boot up my mac.

It's some adobe after effects script. I uninstalled after effects.
I typed in com.aescripts.ZXP-Installer.helper in finder and deleted anything that matched.
I've done a terminal find / -name com.aescripts.ZXP-Installer.helper with no luck.
Don't know what else to do.
First place I'd check is System Preferences:
Users &amp; Groups - Login Items.
Scroll through the list of items there, these will open upon log in (which may be part of your boot process), and delete com.aescripts.ZXP-Installer.helper if it is there.
If not there, try looking in the the following directories:
/Library/StartupItems
/System/Library/StartupItems