Step 1: Open YouTube app. Yes the original YouTube app please.
Step 2: Find song to download.
Step 3: Simply click the share button to download via InsTube.
Step 4: Be amazed as those 0kb values become *mb values.
You're welcome in advance, no thanks necessary!
PS. I honestly created this account like 2 minutes ago just to share this with you[and the rest of the internet too], so I sincerely hope this fixes your problems!