I was trying to export a video (approximately 30 minutes long) but it always cuts off exporting around the 20 minute mark because my disk ran out of storage. Before exporting I have around 200GB free, but while it exports the video takes up loads of storage and eventually the no storage in disk message pops up. It also takes a very long time to export (2-3 hours) and the videos aren't an insane quality (Filmed on an iphone). I have the maximum render quality unchecked and the use previews options checked. If anyone has any advice please let me know 🙂
As Andy suggests the size of your final export is dependant upon the length of your program, your frame size (HD, 4K etc.) and the codec you are exporting to. If you are using a 'pro' codec, such as Prores your files will be big. If you were to choose H.264 then it will be significantly smaller.
In the short term I would suggest you head out and buy yourself a cheap external USB hard drive (at least 1 Terrabyte) and use that to export your program too.