Can I use Booksprout if my book is in Kindle Unlimited? (KDP Select)

Since Kindle Unlimited is a specific program, your best source of support would be Amazon directly. 

We recommend keeping your book OUT of Kindle Unlimited for the duration of your review campaign (from when you list it on Booksprout to the end date).

However here is what we know: technically, it is against the terms of KDP Select so if your book is enrolled in their program currently we don't recommend creating a review campaign with us at the same time. It's best to wait until your 90-day period is up and you've unenrolled. They state your book cannot be available in digital format anywhere except on Amazon while it is currently enrolled in Select. That said, some authors choose to make it available anyway and we haven't heard of any problems yet. If you do choose to do it, it will be at your own risk. If Amazon catches you, there could be some repercussions such as not being able to participate in Select anymore.