Hi katie023,
Thanks for contributing to the Apple Support Communities.
I see that you were forwarding a phishing email to Apple and accidentally clicked a link in the message. From your description, it seems like you saw a misleading pop-up ad or download link.
You've already completed some good steps by clearing your Safari cache and changing your Hotmail password just to be on the safe side. Another thing you can do is remove cookies:
Safari for macOS Sierra: Manage cookies and website data using Safari
By default, Safari accepts cookies and website data only from websites you visit. This helps prevent certain advertisers from storing data on your Mac. You can change options in Safari preferences so that Safari always accepts or always blocks cookies and other website data.
Important: Changing your cookie preferences or removing cookies and website data in Safari may change or remove them in other apps, including Dashboard.
Choose Safari > Preferences, click Privacy, then do any of the following:
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Remove stored cookies and data: Click Manage Website Data, select one or more websites, then click Remove or Remove All.
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Removing the data may reduce tracking, but may also log you out of websites or change website behavior.
Since you didn't install any software or find any files in your Downloads folder, I wouldn't suspect that your Mac is infected.
You can find some additional tips for blocking pop-ups and keeping your Mac safe in
How to block pop-ups in Safari
.
Best Regards.