How to create repeated rows of observations

Please how do I create a form to collect data in the following way:

The clinician picks a date and then enters the patient age, weight, length etc. in a row. The clinician can repeat this process Nth times, before saving the form data.

I tried the guide given in this link

but it did not work, even after tweaking the code it still did not work

Have you tried out the repeat tag on this page?