The Isis Adventure

I'm still at a complete lost for deciphering the clues. I know it can be solved without the clues but I would like them anyway. I know that there is possibly something to do with the words with even number of digits being two digits per letter but I'm still at a loss. Any help would be appreciated.

I think you can pay for them on the website if you do not care to decipher them yourself.
Although I'm not sure if they will offer the kind of help you want. They are not specific instructions

It’s a pretty straightforward substitution puzzle, numbers for letters. When does 2 + 2 = 2?