I did do a restart. FSX is not running.
Then it's the antivirus. Maybe you forgot to disable the default one ( Windows Defender ) ? This, of course, assuming your report:
it says "copying local addon manager module" and a ton of warnings come up saying that bglmanx.dll (3 warning windows in a row), bglmanx_aerosoft.dll, bglmanx_qwings.dll, bglmanx_fbeam.dll, bglmanx.dll again in two windows in a row, bglmanx_fsdt.dat, bglmanx_aerosoft.dat, bglmanx_qwings.dat, and bglmanx_fbeam.dat can't be installed
Which, reading it better, is not entirely accurate, since there are NO files named "bglmanx_aerosoft.dll, bglmanx_qwings.dll, bglmanx_fbeam.dll" that must be installed, so it's not possible you would see a warning about them, since they don't exists. The ONLY file with a .DLL extension is the bglmanx.dll file, and this is the only file that an antivirus will check.
The other files, the one with the .dat extension, will not be checked by any antivirus, but WILL cause an error is FSX is running when you run the installer.
Maybe you have ANOTHER product which works like an antivirus but it's not named as such, like an anti-spyware, an anti ad-aware (the program is defective, of course, since NONE of these files are obviously spyware or ad-ware), they might have the same effect as an antivirus, blocking the files from installing.
The only other possible explanation, but it's very unlikely, is that you are running under a limited user account, and tried to run the installer without giving the admin password, so it cannot write into the FSX folder, because an installer launched from a limited user account doesn't have enough rights to write in the FSX folder (IF FSX is installed under its default locations under C:\Program Files ), if you don't supply it with the admin password.