This is very confusing ... a handful are experiencing file type issues. I think it's browser related.
Just click on the link to download, rather than right clicking and use "save as". This might be causing the extension issue. My 2c.
2007 E92 6MT - Silverstone II with /// Performance Exhaust with ACM Test Pipes and BPM Sport Stage II Dev-Tune - Proper engine warm up, 12-monthly oil change, Castrol TWS 10w-60
2014 F15 X5 3.0d