I ordered a replacement rear wheel that is listed on the website as a replacement for the Soltera and Soltera 2. It is equipped with a Shimano MF-TZ500-7 14-28 Tooth Freewheel, not a cassette. If you have the same rear cluster on your bike then the 8 speed cassette is not compatible. Hope that helps.
I do have a 7 speed 14-28 . The website says it is a cassette. I haven't looked. Maybe it is a freewheel. My question is whether an 8 speed will fit. Be it a cassette or freewheel.
So, you are right, nabob dave. It is a freewheel.
I don't know why some people call them freewheel cassettes ? I always thought it was one or the other.

Thanks for your help.
Now if I can figure out if an 8 speed FREEWHEEL will work.