It means what it says - if BooHoo share price hits 290p (their target) then company will be valued at £3.4billion - slightly more than Asos (assuming their share price stays where it is).
Really? He's already massively incentivised to get the share price up over the next few years. I'd be delighted if he did buy a load but I have my doubts.
Pretty small potatoes and given that these are contractual obligations as part of their remuneration I wouldn't read too much into these director "buys".