Jenny100 I downloaded it from a message from Malwarebytes, so I know that bit is OK,
Previously you said you used a search to find the download:
I managed to do a search and found a download which I tried and got the latest version,
Even if you downloaded using a link in an email message, that link has to point to the URL for a website. The link should have pointed to a MalwareBytes download link --
If you still have that email, check the link it sent you to.
You have to be very careful of what you download and what emails you trust. Even if you're expecting a response from a company like MalwareBytes, don't automatically assume it's not a spoofed email. It's easy to spoof emails and include spoofed links that point to fake antimalware programs. Check all links before downloading and make sure they point to a trusted location. If they point to a site you've never heard of, or if you can't tell what site they point to, go to the website of the software itself (e.g.- to malwarebytes.com) to download the software and don't use the email link.
It is especially important to verify links for antivirus and antimalware software because they are allowed access that other programs don't have. Antivirus have the power to decrypt your Internet traffic so they can scan -- and that includes logging into any banking websites or making purchases over Internet.
There are plenty of fake websites with malware that pretends to be a legitimate program.
MalwareBytes has articles about this. https://blog.malwarebytes.com/threat-ana...-fake-warnings/https://blog.malwarebytes.com/cybercrime/2017/03/drafta-multi-purpose-fake-online-scanner/