Please note that this is a public forum and anyone can see your post.
You have shared a link with your password in it. I have unlisted this topic to protect your account, but should reset your hosting account password as soon as possible.
I have reset your hosting account password for your security. You can find the new password in your client area. Feel free to change it, but do not change it back to the previous password, that has now been compromised.
As for your question itself, the main restriction with Softaculous is that it does not use standard website ports, but cPanel port 2083. Some restricted networks only allow specific network ports, which can result in Softaculous being blocked.
To verify this, you can see if you can open this page: https://demo.cpanel.net:2083 . If you get the same connection error, then you know that access is being blocked on your network. If you do see a login page, don’t bother trying to login, it won’t work.