First, you need to find out the event that has caused the issue.
1. If the issue occurred after you had exported the project on your hosting account, then you need to create correct paths for the files BEFORE exporting your website. Go to Site settings → Export. Then set the following paths:
2. If the problem occurs when you visit any site made on Tilda, then press Ctrl + Shift + I on Windows, or ⌥⌘I on macOS, and open the "Console" tab. If you see something similar (net::ERR-CER_AUTHORITY_INVALID), then the problem must have been caused by the antivirus or a firewall software within your corporate network.
Disable the antivirus protection, or contact the system administrator of your corporate network.