I have two signalinks and they've worked with every windoze and linux computer I've plugged them into without doing anything. First thing I would look at is if it's appearing as a sound card in your system setup. The Signalink does not do rig control, so you can eliminate that as a variable. After that, you have to make sure your digital mode software (FT8) is accessing the Signalink as a source, and not the system sound device. That's pretty much it, I've been using the Signalinks for years and appreciate that they're as close to plug and play digital for ham radio as you're going to get.
Mark K5LXP
Albuquerque, NM