“Use case” is one of those engineering terms that has a specific meaning that has slopped over some into general business parlance to mean something similar but different. Strictly speaking, it’s a description of the interactions among users and systems intended to achieve a certain goal, with “systems” here usually, but not always, referring to computer applications. As you see it commonly used here in Airtable Community and similar venues, though, the non-specific meaning is probably more appropriate (hat tip to Google; I don’t know where they got it):
a specific situation in which a product or service could potentially be used.
Essentially, then, one’s ‘use case’ is the problem one is trying to solve or the process one is trying to automate, optimize, or make less susceptible to error.
Use cases often change and become more refined over time. In your particular instance, at one point your use case presumably was “the need to keep track of [whatever].” which led you to use Airtable. Now, your use case would be “the need to create a new record in Airtable” based on a given input — presumably without manual intervention, since you are considering the use of an integration service. Integration with Integromat would be one possible way of addressing the needs of your use case. Conceivably, at some point you might have an need to define an ever more-specific use case exploring the best way to integrate with Integromat.