Custom Placeholder Template Assitance

Help Please! ( I’m amateur, hobbyist at best)

Goal:
Create a Template with placeholders for “Left Video & Right Video”

I want to insert media in the placeholders & have them have the same size as the placeholders.

I have watched tutorial:
I’ve used the crop tool & nested sequence.
No success yet.

Hopefully this commmunity can help me.

Thanks in advance.

i followed the advice Premiere Gal had in this video But it hasn't worked for me:

• https://youtu.be/lXRNJooXN_o?si=QpwbuulnmA6nxVUJ