Translation:I do not know if I have time for that.
Here, "dazu" can mean both "for it" and "for that". I would even go so far as to say that this is generally the case, though it's difficult to tell without seeing the actual sentences. If DL didn't accept "for it", report it. I don't see how you can translate "dazu" as "to that/it" in this sentence, though.
In German subordinate clauses (e.g. "if I can come", "because he is nice", "when I see him", etc.), the inflected verb comes last. That's different from English. Some examples:
Ich weiß nicht, ob ich Zeit dazu habe. (literally: I know not if I time for that have, i.e. I do not know if I have time for that)
Ich mag ihn, weil er nett ist. (literally: I like him because he nice is, i.e. I like him because he is nice)
Wenn ich ihn sehe, werde ich ihn fragen. (literally: When I him see, will I him ask., i.e. When I see him, I will ask him.)