I don't use Unity, but the best thing to get an answer is to try directly on the official unity forum.
https://forum.unity.com/

I say this, because here there is everything, people who use unreal, godot, etc. In the other forum, 100% of the people who read your post will know about Unity.

You can try to download it directly. https://unity.com/releases/editor/archive

You can also delete your temp files and try again - Appdata / Local / Temp (I think the installation files are placed there.)

Also exclude the folder you're installing Unity in from your anti-virus, because Unity writes 100s of small files, and the anti-virus can interfere with this.