I have recently purchases a GPSMAP67 and it doesn't connect to Basecamp. How do I connect? How do I get my TOPOactive Europe map (on device internal memory)and my other purchased maps (Topo Alps pro and Cycling EU, both on SD-card) on Basecamp?

Using MTP devices on an Mac has some limitations: you can't access the device in Finder (use Android File Transfer instead) and a program has exclusively access to a MTP device. When Garmin Express is installed on your Mac, it will always run in the background by default. This will prevent other programs (like BaseCamp) connecting to the GPSMAP. Change the settings of Express and quit the program before using BaseCamp:
Open Express > Preferences and uncheck "Always keep Garmin Express running in the background"
Quit Garmin Express (cmnd Q) and start BaseCamp.

Thank you! It works. 
Now I still have map transfer (Basecamp doesn’t recognise the TOPO Europe map) and map quality (Cycling map Europe - no detail at all) issues. 

Hello, Install Basecamp: Ensure that you have the latest version of Basecamp installed on your computer. You can download it from the official Garmin website. Connect your GPSMAP 67: Use a USB cable to connect your GPSMAP 67 device to your computer. Make sure the device is powered on. Open Basecamp: Launch Basecamp on your computer. It should automatically detect your connected GPSMAP 67 device. Transfer Maps from GPSMAP 67 to Basecamp: In Basecamp, go to the "Maps" tab and select your GPSMAP 67 device from the list of connected devices. You should see a list of maps installed on the device, including the TOPO active Europe map and any additional maps on the SD card. Select the maps you want to transfer to Basecamp, and click on the "Transfer" button. This will copy the selected maps to your Basecamp library. Accessing Maps in Basecamp: Once the map transfer is complete, you can view and work with the transferred maps in Basecamp. You can use the maps for route planning, waypoint management, and other features offered by Basecamp.  mybkexperience