Fully close out of the app and go into your settings app. Click on "Apps and notifications", then click on ZoomShift. You will see a spot to select permissions. If you click that you can make sure location finding is allowed. You can then re-open the app and you should be able to clock in.
Fully close out of the app and go into your settings app. Click on ZoomShift. Click on location and change it to "While Using". You can then re-open the app, and will be prompted to allow ZoomShift to use your location. Press to allow, and you will then be able to clock-in.