Possibly due to this issue. See response from Garmin.
https://forums.garmin.com/apps-software/mobile-apps-web/f/garmin-connect-mobile-andriod/223310/connect-app-closes-down-when-i-attempt-to-open-an-activity-such-as-running-or-cycling/1052455#1052455
I had the same problem. I deleted the application and downloaded again and it's ok.
ForForce app stop
Clear data
Clear cache
Hey presto!