For posterity, I reached out to TrackLib on this and they say:
Unfortunately, what you want to do is not compatible with our current license. You need to have intent and a possibility for a revenue stream even if we have no lower limit on how much revenue your song must earn.
There’s a ton of free and royalties free stuff on the net or using Creative Commons license. Most of the time the creators just ask for credit. Have you considered to look into that realm?
What if you upload the track to Bandcamp and put some minimum price on it, however small. That shows intent and sets up a revenue stream, even if you never sell a single copy?
Yup. I just had some stuff already made with content from TrackLib, is all.
For sure. But my understanding is releasing a track in a licensed way (say, on Bandcamp) doesn’t then give me the right to then also release it in an unlicensed way (say, on weeklybeats). C’est la vie.