After some playing around I have managed to find a temporary solution, By the looks of it there may be a bug with the native browser inside the Haptics Connect app v 2.0.4 not being able to load hapticsconnect:// urls.
I installed an older version of Haptics Connect (1.9.2) on an Android phone, this is a version of the app that doesn't have the "browser" function. I then logged onto SLR in another window using the Android browser then click the Connect SLR to HC app link and this seems to synchronize with the DeoVR app on Quest 2.
I can't seem to find any solution for running the Haptics Connect app on Quest 2 however, maybe there needs to be a feature within the DeoVR app to click the Connect SLR to HC app link button?