You can easily scan PDFs for specific text in C#, here's how you might do that. We'll follow by using NET Core as our framework, the only nuget package you'll need to install is itext7.
In addition, you'll want to create a folder named "PDFs" in your solution where you will place the file.
We first get the directory which our application will be running with AppContext.BaseDirectory. This allows us to more-easily get to the path of the PDFs folder we created and the PDF inside that.
Next, using the itext7 library, we read the bytes of the PDF file into a PdfReader, and then create a PdfDocument from that PdfReader. The PdfDocument has PdfPages; using the PdfTextExtractor, we can pull out the text from the PDF to check if it contains particular text.