We unpack filez.zip. Inside, there are 3 files:
lul.txt
cc.aspx.lul
Importantfiles.tar.gz.lul

We know from lul.txt that a one time pad was used to encrypt data. It looks like we need to get original cc.aspx. Indeed, using duckduckgo.com to search for cc.aspx reveals a website. After wgetting it, the sizes match. Xor it with cc.aspx.lul to recover key. Although it's shorter than the tar.gz archive, we may recover the beginning of it. Untaring as normal won't work, but we may simply
gzip < decrypted.tar.gz > something

Inside, there's a file called private.pem containing RSA private key. Some parts of it have been redacted. I searched for how such keys are structured and managed to recover public modulus, 255 bits long. I used yafu to factor it (it took about 2 minutes on my macbook). Having the private key, proceed to decrypt the flag (given in problem description).