If it's this one (https://booksprout.co/), it looks like a service that manages your existing ARC team for you, not a discovery platform.

I think it could be useful if you issued a general invitation to anyone on your email list, since they say they filter those who download to pirates or don't review.

I'm pretty careful with who I invite to join my reviewers, so for me it would be better handled just within MailerLite. I don't need another moving piece to deal with. YMMV.