There is a link to the 18+ DLC in the game's description, or you can visit cutiesai's Itch profile to see all of their published games. The DLC is also $2 right now but there is also a free version available as well.
You simply need to download the newest version of 14DWY then delete the previous one. Your save files will automatically carry over.
If you'd like to be safe, you can temporarily move the previous version to another location on your PC, try and run the new version, then delete the previous version once you can confirm that your save files are still there.
For future reference, please keep all DLC related concerns to the DLC's Itch page. This comment section is mainly for the base game (14DWY).
You're welcome to leave a comment on the DLC's Itch page and I'll be happy to assist you there. Just be sure to provide more details on why you aren't able to get the DLC to work.
Unfortunately you will need to download 14DWY. There won't be a browser version as players would not be able to install the DLC, and there is too much lag for those with poor internet quality.
Make sure you're not using a compressed folder to install the DLC. Try to unzip/extract to your desktop beforehand, then use that folder instead of the zipped folder.
Please ensure you've followed the installation guide correctly. Find the "14nightswithyou-paid" folder, then locate and replace it with the "14 Nights With You" folder instead.
