Under Linux, BOINC has to be installed in a special way. In order to run Virtual Machines with VirtualBox in your computer, the user needs special privileges. However, the standard Linux distribution package manager installation for BOINC runs under an unprivileged user, so it will not work with this project. If you have such an existing BOINC client installed, you will have to reinstall it.
First go to the BOINC download link on the official BOINC site and download the installer, which has a name of the form "boinc_VERSION_.sh". This is an auto self-extracting file, that has to be installed as follows: