Raw AVI files are indeed that big, that's normal. Phones and other end-user commercial use or online tools just crunch the quality so that people never have to worry about it. But it can be important for video editors to have files that dont lose information every time they export, so they end up pretty big.
In this case, you have to find a supported "codec", iirc there's a plugin for MP4/MPEG-4 that lets you export a lossy file that still looks nice. It will still end up pretty large, in that case I recommend passing it through handbrake (
https://handbrake.fr), a video compression program that lets you easily select settings like "youtube" or "discord" to get around bitrate limits or size limits while maximizing the quality you can get for the size allowed.