Assuming your project was shot in 1080p24 or 1080p30, your export window output summary should look something like this. You might need to install ProRes in order to export to it. Or you could do DNxHD instead of Apple ProRes (HQ), nothing else would be affected.

with fps being the only variable. (if your source is something other than 29.97, your output should match it.)
This is assuming your sequence was set-up properly to match footage settings as per their “Asset RequireMents”. Also, you can’t have a bug (ie. mtv logo in the corner), credits, or any of the other elements not allowed.
If you do it right, a 3min music video should be about 4-5 GBs.