The HotPot module in the downloads area is from the latest development version of Moodle. It is NOT intended to be used on any of the stable versions of Moodle.
The approved way to update the HotPot module on a site running a "stable" version of Moodle is to update the whole Moodle site. That way you can be sure that all the parts of Moodle work together.
However, if you have modified several standard Moodle files, you may not want to update your whole Moodle site. In this case, I suggest you download the "latest" version of the Moodle that you are using on your Moodle site. Download the Moodle zip file onto your PC, unzip it there, and then upload just the "mod/hotpot" folder to your site.
Since you have only just installed the HotPot module, I presume you have not added any HotPot activities to any of your courses. Therefore, I suggest you remove the HotPot module you just installed, and install the Moodle 1.8 instead.
- remove the Moodle 1.9 HotPot module
- login to Moodle as a Moodle administrator, then select Modules -> Activities, and click "Delete" for the HotPot module
- remove the "mod/hotpot" folder
- using your favorite DB administration program, e.g. phpMyAdmin, delete the "hotpot" record (if there is one) from the "modules" table, and then delete all the "hotpot" tables
- download Moodle 1.8 to your PC
- unzip the file on your PC
- upload "mod/hotpot" from your PC to your Moodle site
- login to Moodle as a Moodle administrator and visit "admin/index.php"
- confirm that the HotPot tables are created without errors
Also, you asked whether the "HotPot" and "HotPot v2.1" downloads should be renamed, but I think the answer "No". The "HotPot" download is always for the latest development version of Moodle, so it's version number is always changing (currently it is 2.4). At some point in the future, I may make the HotPot module backwards compatible again with earlier Moodles, but at the moment, HotPot v2.4 only works on Moodle 1.9
If you have any further problems, please report them here
all the best