That’s a different claim and one with severe tradeoffs for the other option: you can regain access to your Dropbox after losing your password.
Since you’re running their software, you’re ultimately trusting their policies anyway. Even if they had encryption at rest it wouldn’t tell you that it’s correctly implemented and doesn’t e.g. leak keys.
Per your link, Dropbox states only metadata isn't encrypted.
"The actual contents of users’ files are stored in encrypted blocks with this service. Each individual encrypted file block is retrieved based on its hash value, and an additional layer of encryption is provided for all file blocks at rest using a strong cipher."
[1] https://www.dropbox.com/security
[2] https://spideroak.com/no-knowledge/