I gave it a quick try.

The == at the end looked like base64 so:

Decoding "QzBERTgyNDYKCjYzNkY2NDY1M0EzMzM1MzYzNDJDMjA3Mzc1NjI2RDY5NzQy" gives us:

"C0DE8246

636F64653A333536342C207375626D69742"

Bunch of numbers with some letters up to F? Should be hex:

"code:3564, submit"

The final piece can be decoded using the same process to "submit-code".

Middle piece can be decoded to hex: "0746F3A2068747470733A2F2F7873746563682E65752F" but I didn't get past this because this hex gives me a binary that I could not make sense of.

Better luck to the next :P