If a state has 100 delegates and one candidate gets 67% of the vote and the other one gets 33%, they get 67 and 33 delegates respectively.

Different states do it different ways. How they're actually allocated is too crazy to explain in one post here on DU. This sort of explains the process for each state:

https://ballotpedia.org/Democratic_delegate_rules,_2020

The details differ from state to state, but any candidate who earns 15% of the vote or more is going to get some delegates. We are not like the Republicans, who follow a winner-take-all policy. We are the DEMOCRATIC PARTY!

Which is unlike the GOP, winner take all.

and the same is done based on the vote outcome in each congressional district (only a handful of delegates up for grabs for each of the 50-some congressional districts, compared to 100-something for the state total). In the case of the state pool and each district pool separately, a candidate must have at least 15% of the vote in that pool to be included in the dividing-up process for that pool.

At least, that's how I understand it.

But the rules are decided state-by-state. A state could be winner-take-all. A state could be proportional by total state vote only. Etc.

It's far more complicated than that:

https://ballotpedia.org/Democratic_delegate_rules,_2020

from others who were in the race. Klobuchar, Buttigieg & Bloomberg have around 75 between them and Biden may also get some of Warren's 60 too.

Rules are a little complicated for that depending on whether or not a candidate has ended their campaign or merely "suspended" it which you can find online but with those 3 already having endorsed Biden they'll figure out a way to release them and hand off to Joe just in case he needs them because the virus royally screwed up the rest of the primary season. Hopefully Joe will have enough delegates on his own to win it outright on the first ballot without needing any superdelegates or those from others.

Dems have proportional assignments.

This is why Trump was easily able to win the GOP nomination in 2016, even when there were some close contests in some states. He got ALL; runners-up got NONE.

if a candidate gets 15% or more of the vote, that person gets some delegates. If Biden beat Sanders 67% to 20% in Florida, Sanders gets delegates in proportion to his popular vote in the state. The DNC also awards delegates by who wins congressional districts, since Biden won every Florida county and all except one in Illinois, Sanders won't get many congressional district delegates.