As Alpha mentioned above.
Mediafire is a simple way to share bigger files or just packs of them if you see needed, simple to sign up and start managing files so it's a go to site for many that gives out mods or maps or even presets. But as stated earlier you should use the site with caution, the ads that gets displayed there can more than likely give you nasty things on your computer if you're unlucky. I myself got some nasty ransomware from mediafire once all because I wanted to tab back into my browser and accidentally misclicked, I have still used mediafire after that however since it is handy and many think the same.
By being signed up and uploading your files there's nothing wrong at all, it is a legit site used by many but you would want to use it with care like with so many other sites out there.