Great game so far, has made incredible strides since I came on board. Now I start in Sanctum (though I never did the tutorial) with a portal to a planet. My friends have the same thing, but portals leading to different planets.
How to I meet with and play with my friends?
The planet should be based on your geographical region. If all of your friends are also in your geographical region, but are not getting the same planet, something may be wrong.
Regardless, you can meet up with your friends by crafting a warp location picker. (5 bone extract, 5 gold alloy, 1440 spark) Use this to target a planet in the sky above you, then place place warp conduits (5 ancient timber, 5 metamorphic rock) to craft a warp portal, then pass through.
Alternatively, if you meet another player who has warp location tokens for the planet you want, you can have them place a warp for you. This cost the maker 500 coin, so be sure to tip!
Well, by geographical region, if you mean “the same room”, then yes. 
My friend sitting on the left is on a planet I can’t even see in the sky (though we did find one in common). My friend sitting on my right has the same planet as me.
Is there a way to start over the tutorial? Maybe that will get my one friend to the same planet as the rest of us.
Can you name the planets you are seeing? Also, your friend with the wrong planet, does he have his steam client set up to use a different server other than the closest to him? Some people change this to get faster download speeds.
And no, I don’t know of a way to restart the tutorial.
Don’t recall the planets just now (not playing atm), but if he did choose a different server…can that be changed?
It may be too late to change his starter world now, but that would be something worth testing.
The tutorial will currently only trigger for new players.
The Warp in the Sanctum will link to the previous world (and point) you were on before last signing off.
(Assuming nothing is broken) this is because they were originally on different planets when they last signed off.
Since we disabled teleporting between worlds, players were offered the choice of starting world. If you and your friends selected different geolocations options then you will be in different regions.
Not at the moment.
Your best bet is to find someone willing to help you move between the worlds.
Thanks for the detailed reply. No problem…early access!
What planet are y’all on?