The Lab is a parallel course to the Praktikum: Data Science für die Wissenschaften (242424), they share the qualification task and the first half of the classes. As a consequence, students are only allowed to take one of them.
To ensure that all students are on the same page, admission to the Lab is contingent on (1) being familiar with the Data Science 1 lectures and
(2) the submission of a solution to the Lab Qualification Task, which you can find on the ILIAS page of the Lab (linked above).
On ILIAS you will also find additional information regarding the submission deadline and how to submit.