Children’s Apple Music won’t link to Nest Mini

I bought my children (ages 15, 11, and 9) Nest Mini’s for their bedrooms. They all have bedtime routines and bedtime playlists on Apple Music (we have family sharing) and I thought the Nest Mini’s would be perfect for them to use as part of their routine. My oldest was able to link her Apple Music account to hers, but I have not been able to do so with the younger two. We can use the mini’s as Bluetooth speakers, but that’s not why I bought them. I bought the Nest Mini’s so the kids could set up routines within Google Assistant. Is there was way to fix this or is this some arbitrary age restriction set by Apple? I’ve seen others say they had the same issue with both Google Nest and Amazon Alexa, which leads me to believe this issue is on Apple’s end.