The challenge consisted of solving 5 different parts to get each piece of the flag.
Part1 --> %64%73%63%7B%70%75%62%6C%31%63_ --> URL formating. Converts to dsc{publ1c_
Part2 --> (23958575899).toString(35) + String.fromCharCode(0x5F) --> Javascript. Converts to d15pl4y_
Part3 --> 110000 1100110 1011111 --> Binary with leading 0s missing. Converts to 0f_
Part4 --> fq3gq10n_ --> Vignere cipher with key 'alexa'. Converts to ff3ct10n_
Part5 --> YjRubjNkfQ== --> Base64. Converts to b4nn3d}
Parts 1,2,3 and 5 were found as strings within the PDF. Part 4 was found in a text file within a zip file attached at the end of the PDF.
Putting all of those parts together spells out the flag. The flag is dsc{publ1c_d15pl4y_0f_ff3ct10n_b4nn3d}