Downloading your clip from your email can be different depending on your device and browser.
If you're downloading your clip on your desktop computer, usually just clicking on the download link automatically starts downloading the clip. However, in some cases, clicking on the link will open the video in your browser. If that happens, you can right click on the video and press "Save video as..." to download the .mp4.
Another way to download the clip from your email is by right clicking on the "Download your clip" link in the email and pressing "Save as..." to download it to your computer.
When you click on the download link on your iPhone from the email, it automatically opens up a preview of your clip rather than downloading it to your camera roll. However, there are a few ways to download the clip to your phone!
First, you can save the video to your Files on your iPhone, then from your Files you can add it to your camera roll.
If that doesn't work for you, then you can use an app called Documents 5. This app makes it really easy for you to download video files and then upload them to TikTok.
Finally, you can try using a Shortcut. Here's one that works well.
First, use Firefox!
Firefox opens the video you can long press the video (the video itself, not the link to it!), you can press the "Save media" button.
It will then save the video to your downloads. This will work for all videos that support saving in the first place, like by right click in desktop Firefox.