What message do you get if you attempt to try another download of the 32bit trial?
If you follow the download link there is both 32bit and 64bit installations.
Did you check download Microsoft Project 2010 free trial link. It will direct you to TechNet and after you login with your Live Passport, you will be given both 32 and 64 bit edition download links with required activation keys.
Follow the link and try the process one more, this time choose 32bit edition