Cannot start TDE

I have just installed TDE-Trinity in my Stretch box. On boot startx opens x-server-x-org in F7, but the login manager does not appear. /opt/trinity/bin is in the PATH in /etc/profiles, and tdm-trinity is installed, but still no login manager. Surely something else must be necessary to cause the login to appear. I looked for guidance in the TDE instructions, but they are anything but clear. Can somebody help me out? Regards, Ken Heard