How do I make sure my offline stays downloaded? I coulda sworn it was but then I was offline and nothing worked

I am a paid subscriber and have the standalone chrome app, and I thought the files necessary to work offline were there, but then I went offline recently and it wouldnt even play the basic piano template anymore until I got back to internet. How can I check to make sure this doesnt happen again? Thanks

I am still having this issue, any ideas? Where is offline usually stored? On mac. thanks