You're welcome.
What operating system and browser are you using? I would suggest using Mac OS X 10.11.3 El Capitan and Google Chrome 48.
Downloading can be slow sometimes and fast other times, sorry. MEGA may limit bandwidth to users or your connection could be not very good.
Are you on El Capitan? This might work:
https://support.apple.com/en-us/HT202491
1. Click the Apple logo at the top left of your screen
2. Select System Preferences
3. Select Security & Privacy
4. If it is locked, click the lock to unlock and enter your password if applicable.
5. Change setting to Allow apps downloaded from: Anywhere
Use the latest Google Chrome browser and download it.