virtualbox.org

Today I successfully(?) installed virtualbox-6.1_6.1.6-137129~Debian~buster_amd64.deb and Oracle_VM_VirtualBox_Extension_Pack-6.1.6.vbox-extpack on Debian 10 (Buster).

When I wanted to add a new Windows 10 machine only the 32-bit version could be selected.
What is my problem? Do I need the GuestAddition for the 64-bit system?

K.D.J.

Read the related FAQ: FAQ: I have a 64bit host, but can't install 64bit guests.

Thank you very much for the reference.
This article solved my problem: I had to change the BIOS setting.
On my ASUS mainboard PRIME B450-PLUS the relevant setting is found in the section "Advanced -> SVM Mode".
I changed it to 'Enabled'.