how can I re sync my mac to offline downloads

[cleoklarmusica]

Recently I accidentally deleted my mac from my offline devices and I have no idea how to re sync it. I tried to delete and re install the app but it still said on the top as a pop up blue bubble that said 'this device is currently not synced to offline downloads" yet I did not get an explanation as to how to do that. 

If anyone knows how to re sync devices to offline devices please help!!!