Usually, downloading and using a software program shouldn't be a big problem. But now it is. Why? Because literally 99% of these program doesn't work, they contain viruses or they're fake. Pure scams basically.
Therefore your really have to keep a close eye to what software program you download. I suggest that you only download a program which has received many great feedback and which also has obtained a high reputation.
That's the only way to avoid you ending up with a SMS tracking software that doesn't work.