Running my first two Nieces's first game

Looking for advice and hoping this is the right forum.  I am looking at a module I can use to introduce my Nieces to D&D.  We are all in different cities and thought it would be a great chance to keep their minds active and interact in a fun way.  Neither of them has played before and I got them started looking over some youtube videos about game play and character creation but want to find a module that's a good starter for them.  When I play we mostly run in a custom world so I usually haven't gone with modules before but it seems like the easiest intro for them, and would be less for me to worry about as a DM.  Any advice is welcome but Roll20 has a lot of options so hoping someone else has used this platform to D&D and wouldnt mind sharing their thoughts.

How old are they?  I remember playing through S1 with my son when he was 10 -12 and he really enjoyed it.  I think that requires getting all of Saltmarsh though, so maybe someone else will have a good suggestion.

They are around 13, one in OK and one in PA so R20 is really a great platform

For kids that young, just wing it and let them play, build your story around their characters, you'll be surprised at what they and yourself will come up with.

I agree with Ajax, if they want to chase fairies or look for the elusive unicorn then you will have a blast creating trouble for them to get into.

Let me give one piece of hard earned advice. Do not have them approached by a talking dog, who actually turns out to be the bad guy shapeshifted later on. The look of betrayal on their young faces was too much to bear. If you use a talking dog, he just needs their help. Lesson learned. :-) Good luck and have fun!

heheh I may go back to the free-form approach but as an intro I think ill probably go with a one shot and stretch it out a bit with some  improv.  I am inviting their parents as well so hopefully will create little D&D seeds in two different states and give them someone local to bounce offline thoughts off of

I will say also .. if I was local I would be 100% going with unscripted ... this is mostly to give myself some tools to help take them through it on the Roll20 Platform