Sounds to me like the the live remote fed isn’t connected. From memory it’s usually either (red or blue) cable. Find the wiring diagram of the headunit and find which is the live remote. Then you need to connect it to the correlating cable to the adaptor. In the old days you used to swap these cables over depending on what car you were installing the headunit into.
I soldered onto the fused side of number 8 fuse (unused) from the fuse panel,got to it by removing driver's lower dash panel and fusebox back cover,for an ignition feed when fitting an aftermarket bluetooth,you could use that connection if it's the same as S3,just make sure you have/change the fuse to the correct rating for your stereo.