Had my first PC die, rolling a new character to replace him. I'm building him in the campaign, in which a friend is sharing his source books with us all. I'm finding I don't access to the PHB feats, spells in XgtE (Both books he is sharing with us). Was I wrong to assume I would have access to those sources? I also bought the Hexblade class, but don't have access to all of his extended spell list. I am utterly confused. 

In order to access content being shared, you have to check the following:

• Are you making a character in the campaign the content is being shared from (sounds like you are)
• Does someone already in the campaign have a Master Tier subscription? (doesn't have to be the DM, can be anyone in the campaign)
• Has that person enabled content sharing for the campaign?
• Do one or more people already in the campaign that content sharing is enabled for own the books you're trying to access?
• Have you enabled any content toggles (Critical Role, Playtest etc) for the content you're trying to add (sounds like this doesn't apply in your case)

If all of those are true, then you should be able to access the content you're looking for

If all those are true and it’s still not working, have the person with the Master Tier sub turn content sharing off and then back on again.