First of all, why are you running virtual box on Windows 7, as it is still highly unsecure and does not really matter that much if your main OS is infected.

Which distribution are you running on virtualbox? Did you follow the Official installation docs?

It would help alot if you could copy paste the output from your terminal, as without it it is really hard to debug where the error is and why it happens.

Edit: never heard of whonix, so i did not know that it was an OS. Did you go through the https://www.whonix.org/wiki/Money#Electrum