Although a DAW would be much better for this task try this:
1-pick a style
2-set the tempo to 70
3-in the first measure put C.
4-import your audio file and start it on the second measure

The dot after C means rest. You will hear a count in followed by a measure of silence. Your wav will play but the style will not.

In a DAW you can get exactly what you want but this is a BiaB work-around.

Good luck.

I arrived early to a restaurant.
The manager asks, "do you mind waiting a bit?"
I said no.
"Good", he said. "Take these drinks to table 3"

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware