J48 is a Weka implementation of C4.5, so it is able to handle numerical continuous variables. Here is not a problem, for sure.
I am thinking that because you mentioned that J48 is not enabled, it means that you use Weka's Explorer GUI. One thing which is not very nice at that interface is that it supposes that the target variable is the last one. This is not so nice.
After taking a look at the description of the dataset fields found here, you can notice that the first field is an identifier and it ceirtalny should be eliminated from the dataset and the target field is the second one.
I suggest you to try to change the csv file having the target field to be the last one. Perhaps it is possible to do that directly in Weka's Explorer, but I do not know how.
The R's implemenations you mentioned does not have this nasty inconvenient, since you have to specify the independent / dependent variables through a formula using field names, and not based on position.
I did not used Weka since years ago, now I took a look on that again. I use 3.6.11 version. It seems that the things were improved with this problem. So, if you use Weka's Explorer GUI, after you select you data, on the Classify panel, you have the possibility to select the field used as target / dependent variable. This can be done using the combobox placed just upper the start button. After you select the proper target, J48 will be enabled.