You're given a file named token.jwt
that looks like this-
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6MzQsInVzZXJuYW1lIjoiYWRtaW4iLCJwYXNzd29yZCI6InBDVEZ7and0X3QwazNuc19hcjNfZ3IzfSIsImlhdCI6MTU5Njg0NDQxMn0.8hBBZiCJwF5Mp3wLr2AVBcxsS2oybSHlurGPLdHknZs
The answer is right in front of you! Go to jwt.io and copy the token there to decrypt it. You get the flag:
pCTF{jwt_t0k3ns_ar3_gr3}