Does the length of the Cable matter?

Since your TT has a phono preamp built in, there is no problem going with a 15 foot cable. It’s a line level output from the phono preamp to your preamp line level input.  If cable was coming from TT (no phono preamp built in) to your preamp phono input then a short phono cable should be used for best results.
‘Joe Nies

Thanks Joe!

I pulled the trigger on the cable.

👍

For line level gear and speakers no.

Turntables are far below line level gear! The biggest potential issue is noise pick up at that distance.  If it's a mistake you will hear it quickly.

Length  always matters

"Length  always matters"

....what she said.