Maps and DM-ing

I have a DM who I am slowly bringing into the digital world.  I have shown him the power of Maps and he is willing to give it a go. I have been making maps for him.   He has a free subscription to DnDBeyond, but I am master tier.

If he makes a campaign and I join it and share my content, that should be good.  But, then can only he make Maps and edit them?  

Dang.  That's what I thought.

What about allowing someone else to edit a map?  For example, my DM creates a campaign and I have a map I want him to use.  Or vice versa.  

Or, I want to help my less digitally-savvy DM use Maps.  So, I will create the maps and he runs them.  

Does this make sense?