Nowhere I ever said to "disable" your antivirus. I said to be sure the whole Addon Manager is added to the Antivirus EXCLUSIONS and no, "disabling" is not the same thing. So, again, please follow my instructions to the letter and do it again.
And yes, it's perfectly normal you'll have all 4 versions of the Couatl engine (FSX, P3D, MSFS and MSFS 2024), they are always installed, but only the correct one is used in either simulator, and you are not supposed to start it yourself.