Ignoring the questionable translations in Duolingo of the subjunctive as "have to" (it's more like "should" - you add lazima to get "have to" ), that would be
Uje sasa. or
As a subject wa- can only be "they". It's only as an object that it can also mean "you" (pl). Kuja can't take an object because you can't say "I come them“ or anything like that.
Let - after my research, looks like the word " hebu" is useful. ( I found it in " Glosbe" between the sentences as one of many meanings of " hebu" ) For example : (......) HEBU TUjikumbusha chache - but LET US review a few. Or.... HEBU TUchunguze badhi ya kanuni hizo. - LET US look at a few examples.