Open Data in the Welltory app

Select the required category, for example, Activity

Scroll down or tap Sources

Tap icon of the app you need. If the source requires integration with Google Fit, Connect through: Google Fit will be indicated

Tap Connect

If Google Fit isn't connected yet, you will be prompted to connect it.
Choose your Google account and allow access.

Go to source app's Settings and enable data transfer to Google Fit