dnd 5e – How do my spells work when multi-classing Ranger and Druid?

I’ve been reading through posts online and the multi-classing rules over the last couple of hours. And good lord, either I’m an idiot (highly likely) or this stuff is tough. Anyway:

In a campaign I’m playing with some friends, I am multi-classing UA Ranger and PHB Druid. I’m having a few problems with this since there are conflicting sources, I’m also having a hard time understanding that Druids prepare spells yet Rangers in 5e do not. More on that later.

Both of these classes can only learn Druid spells, and Rangers only gain spell slots at level 2. I’m having a hard time figuring out how all these rules fit together with these two specific classes.

For this example, a level 7 Ranger and a level 6 Druid with a Wisdom modifier of +2. Their base spell slots would be:

begin{array}{lccc}
& 1st & 2nd & 3rd \
Ranger & 4 & 3 & – \
Druid & 4 & 3 & 3
end{array}

Which normally would total:

begin{array}{lccc}
& 1st & 2nd & 3rd \
Sum & 8 & 6 & 3 \
end{array}

… but calculating where the character would be on the multi class table would be: (Druid level) + ((Ranger level)/2) which would be 9.5 rounded down to 9. So on the multi-class table the character would have:

begin{array}{lccccc}
& 1st & 2nd & 3rd & 4th & 5th\
Multiclass & 4 & 3 & 3 & 3 & 1 \
end{array}

However neither of my classes at their level can learn 4th or 5th level spells.

Am I correct in saying that I can’t learn 4th and 5th level spells but I could cast a spell such as Cure Wounds in that 5th level slot?

The other problem I run into is that Druids prepare spells (their Druid level + wisdom modifier), which in the case of level 6 could prepare 8. Yet my Ranger does not have to prepare spells how: does that work? Since BOTH classes can only learn Druid spells anyway, can I just stick to “you don’t need to prepare Ranger spells”.

I’m sorry this post is so long but I feel like either I’m doing something HORRIBLY wrong or I’ve just chosen the two most hardest to integrate classes.