If you receive an error message when trying to access a WeTransfer Pro Profile, it's likely to do with the formatting of the Profile URL you've entered into your browser. The error message will vary depending on your browser, but will say something to the effect of: "Your connection is not secure" or "Invalid certificate" and will mention HTTP/HTTPS.
Here's an example of this error in the Google Chrome browser:
The good news here is that this error message is being caused by something really simple: an unnecessary few characters at the beginning of the Profile URL: 'www'.
Normally, 'www.' at the beginning of a URL indicates that a website is being hosted at that domain, since 'www.' is probably the most common subdomain on the Internet today.
With WeTransfer Pro Profiles, though, your chosen Profile URL acts as your subdomain, doing the same job as 'www.' does with regular websites.
So, if you replace the 'www' with the URL of the Profile you're trying to reach, you shouldn't see this warning anymore. For example, instead of: 'www.support-test.wetransfer.com' you should be visiting 'support-test.wetransfer.com'.