A friend has asked me to DM a game for himself and a group of friends.
Said friend has purchased quite a bit of content here on DnD Beyond.

I have an account, but have purchased very little.

If he starts a campaign, and activates content sharing, this would allow myself and the others to utilize that content in creating characters, right?

But, that wouldn't actually allow me to see and edit those characters because I'm not the actual owner of the account that started the campaign and owns the content.

Is that correct?

Is there any way to 'appoint' a DM w/in a campaign so that they have full access?

Any other thoughts or observations which might help in this circumstance?

Thanks!

You, the DM, should make the campaign and send join links. The person with the sub can activate sharing on that campaign (he doesn't have to make the campaign, only be in it) and then you get access to content and can view and edit the character sheets.

Yes.  There is no way to change DMs on a Campaign (it is a sought after feature, but not available).  So you would need to create the Campaign and send out the link.  The player with the content then would enable Sharing on the Campaign and everyone benefits.  I do this for a couple of campaigns and allows others to DM and works really well.  The only thing that would make it better is to be able to shift DMs on the Campaign without ditching one and rebuilding.

Perfect!  Thanks folks!
Now, if the player with the content shares his content with us, will that also allow for me to share any content that I personally have purchased w/in the same Campaign?

Quote from JimFlory >>

Perfect!  Thanks folks!
Now, if the player with the content shares his content with us, will that also allow for me to share any content that I personally have purchased w/in the same Campaign?

 If any one person in the campaign with a Master Tier subscription enables content sharing, then every book purchased by anyone in the campaign will automatically be shared with everyone in the campaign.