Hello breakinglight and welcome to these forums. You'll find many helpful people here and a lot of useful information. Make sure that you:
Try setting it up like this:
(a) right-click in the Track Control Panel (TCP) area below any existing tracks,
(b) select "Insert virtual instrument on new track",
(c) select the VSTi,
(d) click [Yes] on the "Build Routing confirmation" window; that will create tracks for all of the audio outputs from the VSTi,
(e) open the FX window for the VSTi track (click the [fx] button),
(f) select [Options] >> "Build 16 channel of MIDI routing to this track",
(g) disable RecArm on the VSTi track,
(h) if Input Monitoring is Off for the "MIDI" tracks, select them all and turn it on (and turn it on in Preferences >> Track / Send Defaults >> Record config, for future use).
Now you will have 16 tracks sending MIDI (on channels 01 ... 16 respectively) to the VSTi and several tracks for the audio outputs from the VSTi. If you do not need separate MIDI input tracks, omit steps (e) ... (h)
Within the VSTi, load your instruments and set the routing for each one - receiving MIDI on a particular MIDI channel AND sending its audio to a particular audio output pair; depending on the VSTi you may need to do some additional configuration work within the VSTi itself (e.g. to create / enable the output channels).
Back in Reaper, name your MIDI tracks for their destination instruments and add the MIDI. Name the audio tracks too. Colour the tracks as you wish. SAVE them all as a Track Template.