@ptrdahl hard to answer as you haven’t provided any details. Such as when you say you can’t get it to sync, you didn’t say whether you tried to form a sync chain, what’s happening when you try, or what type of information you want synced.
I have a bit of a guide at * How to start a new sync chain and * Adding new devices to existing sync chain
Then there’s also the official guide at https://support.brave.com/hc/en-us/articles/360021218111-How-do-I-set-up-Sync