Measuring task completion

In an effort to measure the usability of my app (a web app) I want to build define a set of metrics.

The first dimension I want to focus on is task completion. E.g. creating users - from all the app users initiating the create user flow, how many manage to actually save that user? how much time do they spend on average creating 1 user? where are they dropping off (where do they go to when they abandon this flow)?

I am looking for an automated way of collecting this information (e.g. google analytics, mixpanel, walkme) so that I can build some metrics that I can monitor month over month and observe how our UI/UX changes are influencing the user experience.

Any thoughts regarding this? Any examples/tutorials on how I could implement this?