Error While Downloading Installation Files

Dear Experts,

I'm running on Windows 10 and I keep having this message while trying to install Bitdefender Antivirus Plus.

There is no problem with my internet connection. I make sure that there is no other antivirus installed and running in my computer, I have turned off real time protection of my Windows Security and also disabled my network firewall. I really appreciate if you can help me on this matter.