Kindly check through each below items to verify: -

1) Temporarily disable any security program, such as Windows Defender, software firewall, hardware (router) firewall, antivirus, phishing filter, ad-blockers from toolbars, that may interfere with the online verification process for the duration of the installation.

2) Adding the related program folder (eg: %ProgramFiles%\Reallusion\Character Creator 3\Bin64\CharacterCreator.exe) and also the folder (C:\Users\Public\Documents\Reallusion) to the Windows Defender white list.
More info: https://docs.microsoft.com/en-us/microsoft-365/security/defender-endpoint/customize-controlled-folders?view=o365-worldwide

3) Make sure that you can connect to our website: -
www.reallusion.com

4) Use Google Chrome as the default browser for the time being and temporarily bypass using a proxy server if you are using one: -
Go to "Control Panel" > "Network And Sharing Center" > "Internet Options" > "Connections" tab -> click on the "LAN Settings" button > un-check "Use a Proxy server..."

Disabled proxy in Windows 10: -
https://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_web/windows-10-build-9879-proxy-server-settings/d7bbc6dd-5539-4e68-93c1-9401468701b5?auth=1

5) To ensure the following registry value is set to 0:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ProxyEnable

6) To disable WinSock Proxy Client: -
https://www.itprotoday.com/management-mobility/how-can-i-bypass-winsock-proxy-client

7) Simply add our 2 websites http://da.reallusion.com and http://widgetcast.reallusion.com to the list of "Trusted sites" in your Windows Internet Options.

i) Go to "Control Panel" > "Network and Sharing Center" > "Internet Options" > "Security" tab > select the "Trusted sites" Zone -> click on the "Sites" button.
ii) Type in our address da.reallusion.com in the "Add this website to the zone" box and click the "Add" button. It's necessary to un-check the "Require server verification (https:) for all sites in this zone" at the bottom of the window before you can add the address.
iii) Repeat the step (ii) with add-in widgetcast.reallusion.com.

8) Ensure the Reallusion website is not listed in the hosts file at "C:\Windows\System32\drivers\etc\hosts". Remove the entry if there is.
https://support.microsoft.com/en-us/help/923947/you-cannot-modify-the-hosts-file-or-the-lmhosts-file-in-windows-vista

*** How to: https://youtu.be/J9gsMGCq9I8

9) Disable IPv6 connection: -
https://networking.grok.lsu.edu/Article.aspx?articleid=17573

10) Click Start, click Control Panel, click "Network and Internet", and then click "Internet Options". Go to "Advanced" tab, make sure 【TLS 1.0】、【TLS 1.1】、【TLS 1.2】are checked.

11) Make sure you login with Administrator privilege on your PC when you install the program.
After this, re-install the Reallusion product.
https://answers.microsoft.com/en-us/windows/forum/all/how-do-i-grant-myself-full-admin-rights/d2b4e3fd-42b6-42f5-b27e-4e33f961f9d1

12) Run "Windows Update" and check whether it is the newest. If Windows is not updated ceaselessly, several issues might occur.

13) Disable "Use automatic configuration script", under Internet Properties > Connections > LAN Settings.

If you still encountered the same issue after this, please contact our Support Team for further assistance.