Without the standalone Addon Manager, I cannot download again without purchasing again..
I'm not sure how you could possibly understand that, considering:
- The stand-alone Addon Manager ( as clearly indicated on each and every page of our site ) is NO LONGER REQUIRED in FSX/P3D. The one and only reason for it to exists was to update the software without downloading the full installers again, and this is something that the Live Update does now, since several years.
- You said you can't "download without purchasing again". How, exactly ? All downloads for FSX/P3D are always freely available on the Download page, you only need to reactivate them using your key.
Also, if you see any strange errors ( especially the last one ), the fault is ALWAYS the antivirus:
- Configure the antivirus to add the WHOLE Addon Manager folder to its Exclusions list.
- Be sure your firewall is not blocking the FSDT Live Update from downloading.
- Download all the installers you need , which will automatically do a Live Update at the end.