Make a disc menu etc in 2021

Here is a long list of tutorial videos

Some are for older versions, but the basic information SHOULD be the same
https://www.youtube.com/watch?v=NG18DktkToI FREE part 1 of 8 for version 2020
https://www.youtube.com/watch?v=j7NCbZUsLqw 2 add media
https://www.youtube.com/watch?v=t7iD-6o6ep4 3 timeline & trimming & auto ripple (alt key to override)
https://www.youtube.com/watch?v=UcaOzJ_7V2s 4 transitions (square box on right with diagonal slice)
https://www.youtube.com/watch?v=XGPtobG8sXQ 5 effects (fx on right)
https://www.youtube.com/watch?v=iAC0Olt3DZA 6 key framing (adjust over time)
https://www.youtube.com/watch?v=6i5SfYvKq0s 7 titles (not show how to insert before/after a clip)
https://www.youtube.com/watch?v=E86tB38yg_w 8 share
https://www.youtube.com/watch?v=xlvxgVREX-Y Handbrake file converter
https://www.youtube.com/watch?v=hUPpc7RUAJ8 add a moving line to a map
https://www.youtube.com/watch?v=s-DDRqM4Jbc Output part of a timeline to a file
https://www.youtube.com/watch?v=fVgrYmoLROk clear stray frames on the timeline
https://www.youtube.com/watch?v=4eyx0tkzkuc change project settings
https://www.youtube.com/watch?v=E3Rech6P0-0 movie menu markers v13
https://www.youtube.com/watch?v=KpGGtH5xvzk customize movie menus v13
https://www.youtube.com/watch?v=PHh2D_CDmeI time lapse guided edit
https://www.youtube.com/watch?v=5u16h83rHIQ L cuts and J cuts
https://www.youtube.com/watch?v=uWM89KZ-yDI introductions
https://www.youtube.com/watch?v=aOPZvWLKtHc tips 1-5 version 13
https://www.youtube.com/watch?v=pYd9iC1QiZ8 tips 6-10 version 13
https://www.youtube.com/watch?v=KPg0J5HXLRk tips 11-15 version 13
https://www.youtube.com/watch?v=-smBkLHZmWc zoom transitions
https://www.youtube.com/watch?v=QO1gWfL6bNM spotlight a person in motion
https://www.youtube.com/watch?v=cIWAvZsx3qo clone yourself
https://www.youtube.com/watch?v=_4xFwiUAaMY V2020 tutorial for beginners
https://www.youtube.com/watch?v=rCItXu6A45E adding text
https://www.youtube.com/watch?v=QDm5QNR240o titles v18
https://www.youtube.com/watch?v=PBNsNF-nrX8 transitions
https://www.youtube.com/watch?v=X265_ZAbaxk slideshow
https://www.youtube.com/watch?v=k1sKZArLONA slide show shortcuts
https://www.youtube.com/watch?v=ziOqbR1Cuy0 music remix v15
https://www.youtube.com/watch?v=xJ_lI90AY00 video collage v15
https://www.youtube.com/watch?v=hjW4UGBZCCI chroma key & videomerge v15
https://www.youtube.com/watch?v=5VIO2aFeGHs 5 PIP effects
https://www.youtube.com/watch?v=JCQn-xAyo-U blur a face v15
https://www.youtube.com/watch?v=zw6opX9E_iU slow motion & fast motion
https://www.youtube.com/watch?v=M5l71denvp0 noise/grain removal tool
https://www.youtube.com/watch?v=0ayCyQ7GZWs how to edit a video
https://www.youtube.com/watch?v=w-i5RQxttx4 another tutorial part 1
https://www.youtube.com/watch?v=lXG1xcbOxLc tutorial for beginners

You do need to be connected to the internet in order to download all of the templates.

Though with all the clipped sentences, it's not exactly clear what your issue is. I don't know what you mean by "There is only one template 6 parts" and "Preview disc video is blank."

It is on a 30 trial.

That may limit what can be done.