You need to select the option you like to install by hitting space bar. This should set an X in front of it. Go back to main screen and choose install
Yes, should be software id 159 or 160
root@DietPiProd:~# dietpi-software list | grep Allo
ID 159 | =0 | Allo GUI full: Audiophile web interface with all dependencies | +Squeezelite +Shairport Sync +Netdata +MariaDB +PHP +Samba Server +NAA daemon +MPD +O!MPD +Avahi-Daemon +Allo GUI +GMediaRender +webserver +Roon Bridge | https://dietpi.com/forum/t/dietpi-allo-com-web-gui-image/1523
ID 160 | =0 | Allo GUI: Audiophile web interface without dependencies |
root@DietPiProd:~#
It is tha simple.