new watch and it is not being seen in Finder or detected by basecamp. I read about Android File Transfter but although the files on the watch show using this, basecamp does not detect watch
You've solved the first part by loading Android File Transfer (AFT). To see the 5+ in Basecamp you do need to make sure AFT is shut down fully. Without diving into Activity Monitor, I find firing up Garmin Express then responding to the message ensures AFT is closed. Not sure I've done anything else to see my 5+ in Basecamp. Are you aware of Garmin Explore? This is probably the way too go now with availability to create courses on smartphones and tablets.
The fenix 5 plus-series watches are MTP interface and do not mount to Mac computers as removable drives. As described in the Support Center article, My Fenix 5 Plus Series Watch is Not Detected by the Computer, Garmin applications can see and interact with MTP devices so you should be able to view your data from the watch in BaseCamp, though you won't be able to access the internal files of the watch.
