spayee/graphy course
Webpage has a sidebar with category and sub-category and each opens just a PDF.
PDF files are stored here - https://randomlettersandnumbers.cloudfront.net/w/o/randomLettersAndNumbers/v/randomLettersAndNumbers/u/randomLettersAndNumbers/p/assets/pdfs/2021/01/13/randomLettersAndNumbers/file.pdf
in this case try to fetch a list and then fetch your cookies from browser, and use curl and scripting to fetch stuff.
for cookies, you can try to open devtools, and then go to network tab, and there find the pdf file, and then right click, and you will find an option something in lines of ‘copy as/for cURL’, copy that, and paste somewhere. repeat exercise for some other file. this should give you some pattern as for how to make a query. it most likely just needs a bearerauth/token in header cookie, or something alike that.