I haven't looked into your devices specifically, but Tentacle makes some affordable gear for timecode sync.
https://tentaclesync.comBut before you get into all that, you need to work through the audio sync workflow as it's described in the manual by the letter.
It does not work like Premiere. For one thing, in Resolve, the organization of your Bin structure matters when you're trying to auto-sync audio.
For another thing, when Resolve syncs your sound, whether by auto or manual, it "links" the files more robustly: the new audio file is treated the same way the old one would have been throughout the rest of the interface. In Premiere, it's more like a timeline/sequence-level association.
I've found that Premiere is generally better at finding a match, but not by such a significant margin that I mind. I'd say that for a bin of 20 clips or so, if Premiere can find all the matches, Resolve might miss two or three. But keeping multitrack audio synced in Premiere with an edit-friendly, nondestructive-delivery-to-audio-dept way is nearly impossible. The best solution I've found involves nested subsequences, which are a nightmare to edit. So, I prefer manually syncing a few clips in Resolve for a generally more pleasant experience afterwards.
Jim's right that keeping the audio as unaltered as possible before you sync should help, but if you aren't getting *any* matches, that's probably not the issue.