it could be a virus

Site creator obviously isn't a native speaker, site itself is of Russian origin. Doesn't stand out as unusual or ill intended on the web end, purely from the mechanical glance I give it. It's basically all the work of one guy uploading a bunch of stuff, if it was made by him or reposting other people's work, I can't say nor have I checked.

I wouldn't toss it out of hand and I'd say it's worth a deeper review from someone who cares, but I'd check multiple files carefully before depending on it at all. In any case, you're safer off using a more established platform anyways.

Like curseforge, planetminecraft and minecraft forum

Never heard of it, but I looked at it, and it looks sketch. If you're looking for mods, maps, packs, and skins, there are plenty of other safe sites out there.