There is no mention how much the rats drank, other than "drank soft drink and/or water ad libitum during 67 days". Did the rats chose coke 100% of the time? 90%? 50%? 1%? Also doesn't mention which specific drink was used, which can be important (specifically, if it contains artificial sweeteners, and which).

I can't view the full text though as it's not on sci-hub and not about to pay $28 to read a single article, so the answers may be in there. But it's not in the article or summary of the paper.